392 MR. E. A. SMITH ON SHELLS FROM ADEN. [Juiie 16, 



recognize the differences which distinguish it. It is a trifle shorter 

 and higher than the Mediterranean form, but chiefly differs in the 

 sculpture. The cancellation is coarser, the radiating ribs are 

 peculiarly and closely imbricately squamate and thicker, and the 

 filled-up portion of the slit is less prominent. These may be 

 regarded by some people as varietal characters, but in answer to 

 this I would remark that if we unite as one species forms from 

 different seas as distinct as those from the Mediterranean and Red 

 Sea, we should be compelled to include others also, such as E. micans, 

 A. Ad., from Torres Straits, and E. Candida, A. Ad., from Adelaide, 

 both of which have certain points of resemblance to E. elongata and 

 to each other, but which still are fairly recognizable as distinct 

 species. 



3. Chiton sictjlus, Gray. 

 (= C. affinis, Issel.) 



C. affinis, Issel, may be regarded as a strongly marked form of 

 the Mediterranean species. There is also a species found in New 

 Zealand, G. siculoides, Cpr. MSS. = C. cereus. Reeve, which is also 

 iiiseparal)le. C. muricatus, A. Adams, from Sydney, and C. stangeri, 

 Recve, = C. insculptus, A. Ad., from New Zealand, are likewise very 

 similar. 



4. Chiton (Acanthochites) discrepans, Brown. 



I cannot separate C. scutiger, Ad. & Reeve., Coreaii Archipelago, 

 and C. carinatus, A. Ad. Si, Augas, from Port Jackson, from 

 this species. 



5. VOLVULA ACUMINATA (BrUg.). 



The two specimens obtained by Mr. MacAndrew are more slender 

 than this species and agree in form viith V. angustata, A. Adams, 

 from the Philippine Islands, and V. cylindrica, Smith, froin 

 Whydah, West Africa, which apparently is the same species. 



6. Philine aperta (L.). 



P. orientalis, A. Adams, and P. angasi, Crosse, both Austra- 

 lian, are inseparable from this species, which also occurs at Natal 

 (Cooke). 



7. (Leuconia denticulata, Mont.) 

 Not considered. 



8. Pecten varius, Linn. 



Mr. MacAndiew collected three specimens which he considered 

 belonged to this species. Of these Mr. (3ooke ' informs us that one 

 is undoubtedly a worn shell of P. senutorius, Gmel. This I fully 



1 Aim. Mag. Nat. Hist. 1886, vol, xvii. i). 134. 



