[399] INVERTEBRATE ANIMALS OF VINEYARD SOUND, ETC. 105 
some closely allied genus, but of this only the asexual form has occurred, 
and it has not yet been carefully studied. This becomes nearly an inch 
long and quite slender. The body is white, with about fifty annulations 
of bright purplish red between the segments, but sometimes a red ring 
‘is absent, leaving wider white bands; the lateral appendages are simple, 
and each has a dot of red on the anterior side; the head is orange, with 
four dark red eyes. 
Of Mollusks there are but few species among the higher groups which 
do not also oceur on the rocky shores at low-water, but of the As- 
cidians and Bryozoa we find numerous additional species. The Gas- 
tropods are represented by the large Fulgur carica (p. 355, Plate XXII, 
fig. 124) and Sycotypus canaliculatus, (p. 359 ;) also by the “ drill,” Urosal- 
pine cinerea, (p. 306, Plate XXI, fig. 116,) which is usually abundant in 
shallow water ; Astyris lunata (p. 106, Plate XX, fig. 110) is abundant on 
the hydroids and alge ; A. zonalis, (Plate X-XI, fig. 111,) which is an allied 
species, of larger size and with plainer colors, is sometimes met with, but 
is rare in this region. It takes its name from two narrow spiral zones of 
white that usually surround the whorls. The Crucibulum striatum 
(Plate X VIII, figs. 125, 126) is often met with clinging firmly to the rocks 
and stones. 
The Leptochiton apiculatus (Plate XXYV, fig. 167) is one of the most 
characteristic and common species on rocky and gravelly bottoms ; 
this also adheres firmly to the stones and dead shells, and its grayish or 
dirty whitish shell, often more or less stained, blends its color with 
that of its surroundings in a way that might deceive the fishes them- 
selves. The back is covered with a series of movable plates, so that 
when removed the animal can curl itself into a ball, like a “ pill-bug,” 
(Oniscus,) or like an armadillo, a habit that it shares in common with 
the scaly annelids, Lepidonotus and Harmothoé, which live in the same 
places with it. The flexibility of the shell also enables the chitons to 
adapt themselves more closely to the uneyen surfaces of the rocks than 
they otherwise could. More rarely the Leptochiton ruber (Plate XXV, 
fig. 166) is met with, though farther north, as in the Bay of Fundy, this 
is a very common species, while the apiculatus is quite unknown there, 
being decidedly southern in its range. The ruber is, as its name implies, 
ared species, and its colors are usually bright and beautifully varied 
with lighter and darker. Its bright color would seem at first a fatal gift, 
calculated to attract the attention of passing fishes, which are always 
fond of such food, but when we examine its habits more closely we find 
that it lives almost exclusively on and among rocks that are incrusted 
by the curious stony alge, known as “ nullipores,” (Lithothamnion poly- 
morphum,) which are red in color, but of various shades, and often com- 
pletely cover the rocks with irregular red incrustations, over large areas 
in shallow water, especially on the coasts farther north, so that this 
shell and a larger species, (C. marmoreus,) usually associated with it, 
are admirably adapted by their colors for living and concealing them- 
