682 THE VOYAGE OF H.M.S. CHALLENGER. 



2. Strebloceras, Carpenter, 1858. 



Strebloceras subannulatum, de Folin (C^cid^e, PI. I. figs. 2, 3). 



Strebloceras subannulatum, de Eolin, Caecidas of the Challenger Expedition, Proc. Zool. Soo. Lond., 



1879, p. 807. 



July 1875. Eeefs off Honolulu. 40 fathoms. Three specimens. 



Testa minuta, bicurvata, vitrea, diaphana, nitida, nucleo spirali, obliquo, anfractibus 

 duobus ; postea testa tubularis, latitudine accrescens, curvam duplicem sequens, transver- 

 sim subannulata, annulis latis, minutissime expressis, subacutis, late separatis. Apertura 

 obliqua. 



Length, 0*12 in. Breadth, 0'02 in. 



These three specimens are the first living representatives of the genus ; and that they really 

 belon^ to it is obvious, since the nucleus exhibits two or two-and-a-half whorls and is placed at the 

 side, not in the central plane of the shell — the position occupied by the nucleus in Ccecum with as 

 many whorls, and in Parastrophia with only half-a-whorl ; and this is a distinction of great import- 

 ance. Below the nucleus the shell increases steadily in breadth, and as it lengthens takes a curve in 

 two planes. The shell is vitreous, translucent, glossy, and thin, ornamented by broad, remote, trans- 

 verse, slightly sharp undulations, which can hardly be reckoned rings, being so faint as only to be 

 visible under the microscope. This ornamentation, slight as it is, is very characteristic. The mouth 

 is oblique, with the obliquity turned towards the plane of the apex of the nucleus. This is a feature 

 of some importance in the family of Ca?cida3, the direction of the oblique mouth being constant in 

 the well-known genera Ccecum, Flem., and Meioceras, Carp. ; and the same may be affirmed of 

 Parastrophia. 



3. Watsonia, de Folin, 1879. 



Testa probabiliter primum nucleosa, postea tubularis, decollata, vix bicurvata, conica. 

 Apertura orbicularis, valde obliqua, valide circumdata. 



The three specimens here under consideration have all the appearances of belonging to the family 

 of the Cascidse. Their form is very peculiar : obviously they have lost the embryonic shell, and the 

 opening thus made has been closed by a septum ; but, unlike the case in Ccecum, only a single 

 decollation has taken place here, leaving the shell acutely conical. On this feature the new genus is 

 founded, which I have dedicated to the Rev. Robert Boog Watson. 



Watsonia elegans, de Folin (CeciDjE, PL I. figs. 4-6). 



Watsonia elegans, de Folin, Caecidae of the Challenger Expedition, Proc. Zool. Soc. Lond., 1879, 

 p. 808. 



Station 186. September 8, 1874. Lat. 10° 30' S. ; long. 142° 18' E. Wednesday 

 Island, Cape York. 8 fathoms. Coral mud. Surface temperature 77° - 2 F. Three 

 specimens. 



