MUSEUM OF COMPARATIVE ZOOLOGY. 53 



their uniformly more slender and cylindrical form and greater posterior attenu- 

 ation. These differences hold good for the young as well as the adults. The 

 outer lip generally rises higher, and the space on the posterior end of the spire 

 is less wide and excavated in S. Watsoni than in the other species, but these 

 characters vary somewhat in both species. I doubt if S. Watsoni ever reaches 

 the size of the Mediterranean form ; the largest I have seen measured 38.0 mm. 

 long by 19.0 mm. in greatest diameter. S. lignarius of the same length gen- 

 erally measures about 24.5 mm. in diameter. 



The magnificent S. nobilis Verrill, first dredged in 1209 fms., off Delaware 

 Bay, was also found in the Gulf of Mexico by the U. S. Fish Commission in 

 1639 fms., at Station 2127. 



Subgenus SABATIA Bellardi. 



Sabatia Bellardi, Bull, della Soc. Malacol. Italiana, II. fas. iii. p. 209, 1876. 

 Sabalia Bellardi, 1. c. sopra tavola C. figs. 5-8. 



Type Sabatia Isseh Bellardi, 1. c, p. 210. 

 Bulla plicata Bellardi, in Sismonda, Syn. Meth. Inv. Pedemont. Fos., 1842 (non 



B. plicata Deshayes). 

 Bulla uniplicata Bell., in Sismonda, ed. ii. 1847. (Nom. inapp.) 



Sabatia bathymophila Dau. 



Plate XVII. Figs 9, 9 b. 



Atys ? bathymophila Dall , Bull. M. C. Z., IX. p. 98, 1881. 



Habitat. Station 33, 1,568 fms.; Station 2, 805 fms.; Yucatan Strait, in 

 640 fms. ; Station 162, in 734 fms. 



The exterior of this species has the general form of Scaphander nobilis, but 

 the minute, sculpture and the characteristics in detail are alike distinct. 



Additional and mature specimens of this species appear in the collections of 

 1878-79, from Station 162, off Guadelupe, in 734 fms., fine gray mud ; bot- 

 tom temperature 40°.0. These specimens show that the truncation of the axis 

 is a character of the immature shell, and that the adult shows nothing of it, 

 but has the body from one end to the other supplied with a broad solid flat- 

 tened callus, which is especially protuberant (into the aperture) at the begin- 

 ning of the posterior third. The outer margin of the callus has a sigmoid 

 curve parallel with the inner outline of the columella and body; the inner 

 margin is, however, somewhat irregularly transversely wrinkled, the mass of 

 callus is much thicker in the middle third, and its surface is ornamented with 

 flattened pustulae irregularly disposed. This gives to the shell an abnormal 

 appearance, which I took, in the single large (but, as we now know, immature) 

 specimen referred to in the description, as an indication of disease in the indi- 

 vidual. More material shows these characters to be normal and constant in 

 their general features in the adult shells. The form of the aperture is well 



