A. E. Verrill— Marine Nemerteans of New England. 445 



Between the intestine and lateral margins, especially posteriorly, the 

 skin is covered with small stellate spots, looking like openings, 

 around which are large numbers of small round reproductive vesi- 

 cles. Color yellowish white. Length, 30 to 40"""; breadth, 12 to 



15""". 



Whole coast of New England ; abundant in Massachusetts Bay- 

 Parasitic in the branchial cavity of the long clam {Mya arenaria). 

 This species is closely related to M. grossa of Europe, and may 



prove to be identical with it. The latter occurs mostly in 3fya 



truncata and Gyprina. Islandica. 



Fig. 9. Malacobiit'lld obrsa, dorsal view, nat. size. 



Malacobdella mercenaria Verriii. 



Malacobdella grosaa Leidy, Proc. Acad. Nat. Sciences Philad., vol. v, p. 209 (non 



Blainville). 

 Malacobdella mercenaria Verrill, Report on Invert, of Vineyard Sound, etc., pp 



458 [164] and 625 [331], 1873. 



Plate xxxix, figure 20. 



Body, in extension, elongated, oblong, with nearly parallel sides, 

 or tapering slightly anteriorly ; ' anterior end broad, obtusely 

 rounded, emarginate in the center, but not deeply fissured. In con- 

 traction the body is broader posteriorly. Dorsal surface a little 

 convex ; lower side flat. Acetabulum round, rather small, about 

 half the diameter of the body in the contracted state, but nearly as 

 broad when the body is fully extended. The intestine shows 

 through the integument distinctly ; it is slender, and makes about 

 seven turns or folds. Color pale yellow, with minute white specks 

 beneath and on the upper surface anteriorly, giving it a hoary ap- 

 pearance ; middle of the dorsal surface irregularly marked with 

 flake-white ; laterally reticulated with fine white lines. 



Length in extension, 25'"'" ; breadth, 4'""' ; in partial contraction, 

 18'""" long ; 5 to 6'^"" wide. 



New Haven, parasitic in the branchial cavity of the round clam 

 {Venus mercenaria), October, 1871. Philadelphia, in the same 

 species of clam (Leidy). 



