[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 I 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. 

 239, 240) occurred adhering to dead shells. The Modiolaria corrugata 

 (Plate XXXI, fig. 235) was dredged several times in the deepest local- 

 ities, but M. Icevigala, recorded by Mr. Sanderson Smith, was not met 

 with by us ; nor Leda tenuisulcata, which has been found off Newport, 

 Khode Island. The Nucula, delpliinodonta (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 XXVII, fig. 197) were frequently 

 dredged. The specimens of Thracia truncatn (Plate XXVII, fig. 195) 

 were few and small. The Cryptodon obesus V., (Plate XXIX, 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. C. Gouldil (Plate xxix, fig. 213,) is more 

 common. Yoldia sapotilla (Plate XXX, 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 Eugyra 

 pilulariSj (Plate XXXIII, 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 

 tbe Boston Society of Natural History. 



