[509] INVERTEBRATE ANIMALS OF VINEYARD SOUND, ETC. 215 
although quite variable in form and sculpture, are generally compressed ; 
those from this region are mostly rather swollen, and often decidedly 
obese. These correspond with the type-specimen of A. lutea PERKINS, 
from New Haven, (fig. 3,) which I have been able, through the kindness 
of Dr. Perkins, to compare directly with our specimens. This form is, 
perhaps, sufficiently well marked to be designated a sa variety, (lutea, ) 
but many specimens intermediate between this and the ordinary forms 
occurred, This variety resembles the European A. sulcata more closely 
than do any of the other varieties of our species, but in the character 
of the hinge, lunule, beaks, and sculpture, it differs decidedly from any 
European specimens that [ have seen. The Astarte quadrans (Plate 
XXIX, fig. 205) was rarely met with. Good-sized specimens of the 
large scollop, Pecten tenuicostatus, were dredged off Gay Head on hard 
bottoms, and also on the muddy bottom, in 29 fathoms, and in several 
other localities. The northern Anomia aculeata (Plate XXXII, figs. 
259,240) occurred adhering to dead shells. The Modiolaria corrugata 
(Plate XX XI, fig. 235) was dredged several times in the deepest local- 
ities, but MW. levigata, recorded by Mr. Sanderson Smith, was not met 
with by us; nor Leda tenuisulcata, which has been found off Newport, 
Rhode Island. The Nucula delphinodonta (Plate XXX, fig. 229) was 
common on soft muddy bottoms. The Lucina filosa (Plate XXIX, fig. 
212) appeared to be not uncommon on similar bottoms, but most of the 
specimens obtained were less than an inch in diameter. Small speci- 
mens of Periploma papyracea (Plate XX VII, fig. 197) were frequently 
dredged. The specimens of Thracia truncata (Plate XXVII, fig. 195) 
were few and small. The Cryptodon obesus V., (Plate X XIX, fig. 214,) 
was first discovered in this region, but all the specimens were of large 
size and dead, though mostly quite fresh. I have since seen smaller 
specimens from Labrador, &c. OC. Gouldii (Plate xxix, fig. 213,) is more 
common. Yoldia sapotilla (Plate X XX, fig. 231) was generally abundant, 
especially in the soft mud, but Y. obesa was only met with once, and 
in small numbers, in 29 fathoms; Y. thraci-formis we did not meet with, 
but Dr. Simpson records it from off Long Island. 
Of Ascidians very few species occur. The most abundant is Lugyra 
pilularis, (Plate XX XIII, fig. 249,) which, in contraction, looks like a 
round ball of mud, for it completely covers itself with a thick coating 
of fine sand or mud, which is held in place partly by delicate fibrous 
processes from the integument, those from the base being longer, and 
serving to anchor the little creature in the sand by attaching a con- 
siderable quantity of sand to themselves. When the sand is removed, 
the integument is found to be thin and quite translucent, the tubes, 
when extended, are long and transparent, close together, and inclosed 
by a naked band which surrounds the base of both. It is also very 
Figure 3. Original figure of Astarte lutea, natural size. From the Proceedings of 
the Boston Society of Natural History. 
