V T889. n '] PROCEEDINGS OF THE NATIONAL MUSEUM. 279 



Family CUSPLDARIID^E. 

 Genus CUSPIDARIA Nardo. 



Ctispidaria Nardo, Revue zool., p. 30, Jan., 1840. 

 Kecera Gray (1834), not of Robineau Desvoidy (1830). 

 Ctispidaria Ball, Bull. Mils. Comp. Zool., xn, p. 292, Sept., 188(5. 



Cuspidaria patagonica Smith. 



JSfewra patagonica Sjiith, Challenger Laruellibrauchs p. 39, PI. vil, Figs. 5, ba-b, 1885. 



Hab. — TJ. S. Fish Coin mission Station 2751, in 087 fathoms, ooze, off 

 St. Kitts, West Jndies, temperature 40° F. Station 2791*, off Manta, 

 Ecuador, in 401 fathoms, mud, temperature 43°, etc. 



A fine specimen of this species, measuring 44""" in length and 14 mm 

 in transverse diameter, was dredged off Manta ; other specimens were 

 found in dredgings from the whole eastern coast of South America, the 

 western coast of that continent, and northward as far as Lower Califor- 

 nia. The larger specimen afforded the following notes. 



The siphonal septum, by which name I shall refer to the dividing 

 septum of the peripedal chamber, extends forward from the proximal 

 end of the siphons to the anterior adductor. It is divisible into three 

 areas, a longitudinal central muscular area occupying about two-thirds 

 of the whole septum, and on each side a less muscular, thin, and tense 

 membranous strip, which is connected with the inside of the valves and 

 leaves the imprint on the shell which would ordinarily be taken for the 

 outline of the "pallial sinus." The central muscular area is attached by 

 a bundle of muscular fibers above each adductor on each side of the 

 median line. All four points of attachment leave well-marked scars on 

 the shell. 1 have shown elsewhere that these muscles, if not homolo- 

 gous with, at least perform the functions of the siphonal retractors of 

 ordinary Pelecypods, aud in forms like Poromya mactroides, where the 

 usual retractors are present, the siphonal septum is destitute of muscu- 

 larity, or possesses it only to an inferior degree. The posterior septal 

 muscles are smaller and rounder in section, more vertical in direction, 

 and more widely separated from each other than the anterior pair. 'The 

 latter are narrow and elongated on their surface of insertion, and but 

 for the separation of the valves would nearly touch in the median line. 

 The principal body of fibers on the plane of the septum is longitudi- 

 inally arranged ; another series crosses the septum in an arched man- 

 ner toward its extremities, especially behind, while there are indi- 

 cations of still smaller series of more or less radiating fibers knitting 

 the whole fabric together and to the shell. 



The siphonal septum in this species divides the cavity of the shell 

 unequally, the upper portion being smaller than the lower. In the up- 

 per, sustained especially by a median fibrous mesenteric band, is sus- 

 pended the visceral sac. Viewed from above, it is subcordate in pro- 

 file; from the side it seems acutely ovoid. It occupies, as contracted 

 by alcohol, about haif the cavity above the septum. The valve of the 



