[371] INVERTEBRATE ANIMALS OF VINEYARD SOUND, ETC. U7 
on muddy shores, burrowing beneath the surface, at or just below low- 
water mark. 
Many of the Annelids found on muddy shores occur also on sandy 
shores, especially where there is a mixture of mud with the sand, and 
consequently they have been mentioned in the preceding pages. 
Among these are Nereis virens (p. 317, Plate XI, figs. 47-50) and N. 
limbata, (p. 318, Plate XI, fig. 51,) both of which are common on muddy 
shores ; also Diopatra cuprea, (p. 320, Plate XIII, figs. 67 and 68;) Lum. 
briconereis opalina, (p. 342, Plate XIII, figs. 69, 70;) LD. tenuis, (p. 342;) 
Maldane elongata, (p. 343;) Notomastus luridus, (p. 342 ;) Notomastus fili- 
formis, (p. 342;) Cirratulus grandis, (p. 319, Plate XV, figs. 80, 81;) Cis. 
tenides Gouldii, (p. 323, Plate XVII, figs. 87, 87a;) all of which are 
found both in mud and sand, but prefer, perhaps, a mixture of the two. 
Rhynchobolus Americanus (p. 342, Plate X, figs. 45, 46) and R. dibran- 
chiatus (p. 341, Plate X, figs. 43, 44) are also found in mud, though per- 
haps more common in fine sand, or sandy mud. 
The “ blood-drop,” Polycirrus eximius, (p. 320, Plate XVI, fig. 85) is 
however, a species that belongs properly to muddy localities, and it de- 
lights in the softest and stickiest mud of the shores, near low-water 
mark. The larger blood-drop, Cheetobranchus sanguineus, (p. 320,) is also 
found in similar situations, and the soft mud, filled with decaying veg- 
etable matter, seems to be its most congenial home. 
Of Mollusks there are comparatively few species that are peculiar to 
muddy shores, but there are many that live almost equally well in such 
localities and on shores or bottoms of other kinds. 
Among the Gastropods, the proper mud-dwelling species are few. 
The Ilyanassa obsoleta (p. 354, Plate XXI, fig. 113) is the most abund- 
ant, for it occurs everywhere over the mud-flats in great numbers, and, 
in cold weather, often crowds in large numbers into the pools left on 
the flats. The Nassa vibexr (Plate X NI, fig. 114) has nearly the same 
habits, but is comparatively rare. Itis more frequently found among 
the eel-grass, and is more common farther south. 
The Eupleura caudata (Plate XNI, fig. 117) is usually found rather 
sparingly in this region, but in one locality, at Waquoit, it occurred in 
considerable numbers in the small streams and ditches in the muddy 
marshes near the shore. It occurs occasionally at low-water, but is 
more often met with on muddy and shelly bottoms in the shallow water 
of the bays and sounds, and is much more common farther south. The 
Crepidulu convera (p. 355, Plate XXIII, fig. 128) is very common on 
the shells of Ilyanassa obsoleta, especially when they are inhabited by 
“hermit-crabs.” It is also frequently found on the eel-grass, where, in 
August, it often deposits its bright yellow eggs inclosed in small, gela- 
tinous masses, which are grouped in clusters. 
The Bulla solitaria (Plate XXV, fig. 161) is a species restricted to 
muddy shores and bottoms, in sheltered situations, and is found also in 
muddy ponds and estuaries. The color of the animal of this species is 
