1891.] MR. E. A. SMITH ON SHELLS FROM ADEN. 403 



when a very large series of specimens is examined, which will 

 separate any of these so-called species from the rest. 



Sowerby (Proc. Zool. Soc. 1882, p. 120), on the other hand, 

 observes "having had exceptional opportunities, from time to time, 

 of examining large numbers of specimens of all the varieties, I 

 continue to regard these last (C. abbas, C . panniculus, C. legatus, 

 &c.) as species." 



24. CoNus NussATELLA, Linn. 



Hab. Red Sea, East Africa, Ceylon, Java, PhiUppines, N. Aus- 

 tralia, New Caledonia, Polynesia. 



25. Terebra tessellata, Gray. 

 Hab. Pidang, Sumatra. 



This species is quite distinct from T. ligata, Hinds, with which 

 it is united by Tryon'. It is, however, identical with T. decorata, 

 Deshayes. Having the types of the three so-called species in the 

 Museum, I can speak with certainty upon the subject. 



The specimens from Aden show that this species attains to much 

 larger dimensions than those already quoted, the largest example 

 having a length of 55 millimetres. 



26. Terebra lamarckii, Kiener. 



Hab. Zanzibar ; Aden ? (Jousseaume as duplicatu). 



This species is considered by Tryon and Reeve a variety of 

 T. duplicata, Linne. The style of coloration, however, is very 

 peculiar, and the longitudinal striae are farther apart. I prefer 

 therefore, not having as yet met with intermediate forms, to regard 

 them as distinct species. 



27. Terebra (Impages) c^rulescens, Lamarck. 



Hab. Red Sea, Mauritius, Philii)pines, Australia, Polynesia. 



28. Pleurotoma violacea. Hinds, var. 



Hab. Red Sea, Persian Gulf, Japan, Philippines, New Guinea, 

 New Zealand, Australia. 



The specimens from Aden are unusually large, measuring as 

 much as 27 millimetres in length and 9 in diameter. They do 

 not belong to the typical lilac form, but are of a very light brownish 

 tint with white spiral ridges, one of which is more conspicuous than 

 the rest. 



29. Pleurotoma (Surcula) catena. Reeve. 



This species, the habitat of which was hitherto unknown, is well 

 distinguished by the oblique white tubercles on the middle of the 

 wliorls with brownish spots between them. They become obsolete 

 on the body-whorl, which is ornamented with oblique streaks and 



' Man. Conch, vol. vii. p. 2(). 



