DALL: MOLLUSCA AND BRACHIOPODA, 331 
to consider the formation of a new genus. The discovery of a similar base in a 
living Species H. “mitrata Gmelin” of Defrance (H. antiquata Linné) confirmed 
him in this opinion, and. he proceeded to publish his new genus, leaving the other 
Species of Pileopsis Lamarck, which were believed to form no shelly base, to be 
Brouped separately. "The shelly base alone might not be considered a sufficient 
Character to found a genus upon, but the wide differences of anatomy which are 
Claimed to exist between Capulus and Hipponix, if confirmed by more modern 
examination, are of even more than generic importance. H. “mitrata " being the 
first Species in Defrance’s list, might naturally serve as type, though the genus is 
known really to have been founded on H. cornucopiae ; but as they are both with- 
out any doubt congenerio, the question becomes unimportant. As Defrance in 
Using his new name terminated his specific names in a, it follows that he regarded 
the name as feminine, and subsequent writers should not try to alter this on the 
Asis of an assumption. The smooth, deep-water species separated by Mr. Mel- 
vill have a peculiar facies, but perhaps hardly of subgeneric value. The slight 
portance of surface sculpture as indicative of systematic differences of such 
Value is illustrated by the following species which unites in a single individual the 
characteristics of two such discrepant species as 77. antiquata and H. subrufa 
Hipponix delicata Darı, n. sp. 
Shell solid, conical, the apex in the posterior third of the length, erect, blunt; 
e posterior slope steep, the anterior much longer, gentle, near the apex almost a 
lttle concave ; shell substance porcellanous, greenish-white, the muscular impres- 
Slons more translucent, and darker colored; sculpture of the apical third concen- 
trically lamellose, as in H. antiquata L., the remainder of the shell continuous 
With irregular but not lamellar narrow waves, delicately, evenly, radiately grooved ; 
‘nterior polished, with a thick smooth peritreme. Alt. 5; lon. 11; lat. 9 mm, 
ìe apex 3.5 mm. in front of the posterior edge. 
U. 8. 8, “Albatross,” station 3355, Gulf of Panama, in 182 fathoms, mud, 
bottom temperature 549 F. U. S. N. Mus. 193,041. ; 
Die curious combination of lamellose and radial sculpture, usually found in 
ferent Species, marks this one as unique. The radial striation is finer than in 
My of the well-known shallow water species. The shell is fresh, though it did 
Rot contain the animal. 
Hipponix barbata Sowzmnr. 
Hipponys barbatus Sowerby, P. Z. S. Lond., 1836, p. 5; Thes. Conch., Brachiopoda, 
P. 369, pl. 73, figs. 26, 27. 
Bench, Chatham Island, Galapagos Islands, U. S. S. “ Albatross.” U.S. N. 
us, 96,044, 
his Species is widely distributed and is reported as far north as the Gulf of 
alifornia, 
