[Jordan and Evermann, 1896-1900, p. 2116.]
This little fish resembles the sea snail (p. 464) so closely, especially in its tadpole-like form, in the presence of a sucking disk on its chest, in which the rays of the ventrals (reduced to mere knobs) serve as a central support, and in the peculiar outline of the pectoral fins with secondary frilled basal lobes, that it is difficult to distinguish one from the other. The most obvious difference between the two species is that there is no indentation between the spiny and the soft parts of the dorsal fin in the striped sea snail. Furthermore, it usually has 33-35 rays in the soft portion of its dorsal fin and 26-29 rays in its anal fin, as against a maximum of 32 dorsal rays and of 27 anal rays in the other sea snail (p. 464). And the separation between the dorsal and anal fins and its caudal fin is not as definite in the striped sea snail as it is in the preceding species; in fact it is sometimes difficult to draw a sharp line between the fins. A minor character, which gives the head a rather different aspect, is that the dorsal profile is more arched in the striped sea snail.
Many color varieties of this fish have been described and named. As a rule the ground tint is of a shade of olive green, gray, or brown, variously tinged with reddish, with yellowish, or with lilac, and but little paler below than above. Red ones with pale and dark stripes have been seen among kelp in New England waters. And they are dark and pale in endless variety in varying situations, some nearly plain, some definitely striped with few or many narrow longitudinal bands, others spotted. In fact no two are alike. Usually the fins are darkly blotched or barred.
This fish grows to a length of 10 inches in Arctic seas but very few of them are more than 5 inches long in temperate latitudes.
All that is known of its habits in our Gulf is that it lives on rocky or stony bottom, usually among the stalks and roots of kelp to which it sometimes clings fast, a habit which European writers describe as common. In British waters it is often to be found hiding in the tiny pools of water that are left under pebbles by the ebbing tide, and probably a search of the beaches would reveal it in similar situations in the Gulf of Maine also. Small ones often live inside the shells of the giant scallop (Pecten magellanicus), and it is our impression (though not backed by any definite evidence) that this is a more usual habit with the striped sea snail than with the preceding one (p. 465). At any rate, W. F. Clapp informs us that it is the rule to find at least one or two striped sea snails in a bushel or so of sea scallops, and fishermen have told us that sea snails of one species or the other (probably of both species) are found in scallop shells on Georges Bank.
Small crustaceans, chiefly amphipods and shrimps of various kinds, have been found in the stomachs of striped sea snails on both sides of the Atlantic; they also feed on small shellfish, and they were described by Fabricius as eating small fish fry and algae.[page 467]
This is a winter-spring spawner; females are full of roe at Woods Hole in December and January, and the collection of the Museum of Comparative Zoology contains a female distended with eggs that was taken on April 1 many years ago. Larvae only 5.5 mm. long, which we towed near the Isles of Shoals on July 22 and in Massachusetts Bay on August 31 in 1912, must have been hatched from eggs spawned at least as late as May, if not in June.
The eggs, about 1.5 mm. (0.06-inch) in diameter, sink and stick together in bunches, to hydroids, seaweeds, or other objects, like those of Neoliparis atlanticus, and it seems that incubation is about as long as it is with the latter, i. e., at least a month. The larvae are about 5.5 mm. long at hatching and they live adrift until they are upward of 16 mm. long, when the sucking disk is well developed.
Arctic and North Temperate Atlantic; north to the White Sea, Spitzbergen, Greenland, Davis Strait, and northern Labrador, and reported from the Kara Sea and from the Arctic Ocean north of Siberia; south to northern France and to Delaware Bay and Virginia.
The distribution of this sea snail parallels that of the preceding species in our Gulf. Thus it has been dredged not uncommonly in the Bay of Fundy region in from 5 to 100 fathoms and has been recorded from Grand Manan; from Eastport, as well as from other localities on the Maine coast; here and there about Massachusetts Bay; and on Georges Bank; also at Woods Hole.
It has been described as "common" in the southern part of the Gulf of St. Lawrence; has been reported in the estuary of the St. Lawrence River; at Anticosti; and in the northeastern part of the Gulf; also off the south coast of Newfoundland; in Conception Bay; off the eastern end of the Strait of Belle Isle; off the southeastern Labrador coast, and from Fort Chimo, on Ungava Bay, in northern Labrador, as well as from West Greenland.
It is of no commercial importance.
 Fauna Groenlandica, 1780, p. 137.
 The following lines are condensed from Ehrenbaum's (Nordisches Plankton, vol. 1, 1905-1909, p. 112) account of its eggs and larvae in European waters.
 This sea snail, formerly known only as far south as New York, has been taken off Delaware Bay by Albatross II, and off Assateague, Virginia, by the Grampus (Welsh, Copeia, No. 18, 1915, p. 2).
 Jones, Proc. Nova Scotian Inst. Sci., vol. 5, pt. 1, 1882, p. 89.
 Vladykov and McKenzie, Proc. Nova Scotian Inst. Sci., vol. 19, 1935, p. 99.
 Cox, Contrib. Canadian Biol. (1918-1920) 1921, p. 112.
 From the cruises of the Newfoundland Research Commission.
 Packard Proc. Portland Soc. Nat. Hist., vol. 2, No. 13, 1909, p. 112.