MOLLUSCA. 16 



versely flattened spines. A second smaller series adorns the last whorl, and 

 beneath this are two or three small ribs. The only specimen obtained is dead, 

 and with no other colour than what it has acquired by lying in the mud without 

 its animal. 



Family — Pleurotomace.e. 

 Pleurotoma. Lamarck. 



37. Pleurotoma nohilis, Hinds, Proceed. Zool. Soc. 1843, p. 37, (Plate V. fig. 1, 2.) Testa 

 fusiformi, solida, rugosa ; anfractibus superne concavis, leviter striatis, prope mediam carina maxima, 

 inferne, prsecipue ultimo, carinis parvis alternantibus ; sutura simplici ; labio externo subintegro, in- 

 terno inferne paululum producto ; epidermide pallide fusca, induta. 



Inhab. San Bias, Mexico. From seven fathoms, among mud. 



This is a very considerably larger shell than P. oxytropis, but in the 

 character of the sculpture they closely approach each other. It is chiefly 

 distinguishable from it in the absence of any keel between the principal keel and 

 the suture, and in some minor characters. 



38. Pleurotoma jubata, Hinds, 1. c. p. 37, (Plate V. fig. 3.) Testa, fusiformi, acuminata, 

 laevigata., fulva; anfractibus medio carinatis, superne granulis uniseriatim cinctis, inferne carina 

 parva. unica, sed ultimo pluribus ; sutura carinata ; canali breviusculo. 



Inhab. The China Sea and north coast of Sumatra. Dredged from a 

 muddy bottom in eighteen fathoms. 



A solid horn-coloured shell, the principal keel sharp, and slightly paler, with 

 a secondary keel above, interruptedly transversely granular ; the suture is also 

 keeled. Aperture with the canal shorter than the spire ; inner lip produced. 



39. Pleurotoma gemmata, Hinds, 1. c. p. 37. (Plate V. fig. 4.) Testa, fusiformi, elongata, gra- 

 cillima, fusca. ; anfractibus numerosis, medio uniseriatim tuberculato-carinatis ; tuberculis rectis, 

 subquadratis, albidis ; carinis duabus, parvis, suturam comitantibus, anfractu ultimo multicarinatis ; 

 sinu laterali pone carinam ; apertuia ovali ; canali elongato. 



Inhab. Gulf of Magdalena, California. Obtained from seven fathoms, 

 among sandy mud. 



Elegantly fusiform, with a prominent principal keel composed of squarish 

 tuberculations. 



40. Pleurotoma stolida, Hinds, 1. c. p. 37, (Plate V. fig. 5.) Testa, fusiformi, Icevigata, 

 cornea; anfractibus superne planulatis, inferne costatis; costulis albidis, brevibus, obliquis, in an- 

 fractu ultimo evanidis ; apice papillari ; sutura simplici ; canali brevi ; labio externo tenui. 



