ZOOLOGY OF PERNANDO NOEOIS'HA. 



491 



22. LiTTORiNA TROcniFORMis, var. ? (Plate XXX. fig. 2.) 

 Littorina trochiformis, Dillwyn, Philippi, Abhild. vol. ii. p. 143, pi. ii. 



ff. 12, 14, 15. 



Littorina nodulosa, Watson {non Gmelin), 'Challenger' Gasteropoda, 



p. 577. 



Testa parva, fusiformi-ovata, grisea vel nigrescens, albo-nodosa ; 

 anfractus 6-7, convexiusculi, superiores granorum seriebus tribus 

 ornati, striisque spiralibus elevatis paucis sculpti, ultimiia in 

 medio obtuse angulatus, seriebus quatuor cinctus, ad basim albo 

 punctatus ; apertura nigra, fascia basali pallida ornata, inferne 

 subacuminata ; columella lata, purpurea, superne macula lutes- 

 centi notata. 



Longit. 19 mill., diam. 10. Apertura 7 longa, 6 lata. 

 )? 11 5> J5 9. ,, 6|- ,, 5 „ 



The above measurements of two specimens from Fernando 

 Noronba show tbe variation in the form of this variety. The 

 white tubercles are rather acute in some specimens, whilst in 

 others they are scarcely raised above the surface. On the body- 

 whorl there are two approximated series at the periphery and 

 two above, and at the base is a tesselation of white and dark 

 spots. 



The shells quoted by Mr. Watson from Fernando Noronha are 

 certainly specifically the same as those obtained by Mr. Ridley, 

 and are, I think, almost specifically distinct from the L. nodulosa 

 of d'Orbigny. They have less angular whorls and less acute 

 nodules, of which there are two series on the body -whorl above 

 the two principal series at the periphery, whilst in L. trocliiformis 

 (^—nodulosa, d'Orb.) there is only a single series. The aperture, 

 also, of the Fernando shells is darker and none of them exhibit a 

 second pale zone at the upper part, which is nearly always visible 

 in the West-Indian species. 



23. Littorina angulifera {Lamarck). 



Litorina angulifera, Philippi, Ahbild. vol. ii. p. 223, pi. v. ff. 12-15. 

 Rah. West Indies, West Africa and Pacific {Phil.). 

 Only a single young specimen was obtained by Mr. Eidley ; it 

 agrees in all particulars with West-Indian specimens. 



24. ToRiNiA iETHioPS {MeiiJce) . 

 Hah. West Indies. 



Both Philippi and Hanley,in their respective monographs, admit 

 this as a distinct species, but I am inclined to think with the 



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