REPORT ON THE GASTEROPODA. 55 



Ziziphinus exiguus, Adams, Monog. Trochid., Proc. Zool. Soc. Lond., 1851, p. 165, No. 25. 



„ exasperatus, Reeve, Conch. Icon., vol. xiv. pi. viii. fig. 54. 

 Trochus exasperatus, Jeffreys, Brit. Concb., vol. iii. p. 324, and vol. v. p. 203, pi. lxiii. fig. 3. 

 „ „ Hidalgo, Moll. test, rnarins Espagne, Journ. de conch., vol. xv. p. 401, sp. 6. 



„ exiguus, "Weinkauff, Conch, d. Mittelm., vol. ii. p. 365, sp. 10. 

 ,, exasperatus, Aradas and Benoit, Conch, viv. Sicil., p. 161, No. 433. 

 Monterosato, Conch, foss. Monte Pellegrino, p. 29. 

 Monterosato, Enumeraz., p. 22. 



Fischer in Kiener's Iconog., p. 266, sp. 147, pi. lxxxix. fig. 1. 

 Seguenza, Formaz. Terz., pp. 272, 320, 356. 



Jeffreys, "Lightning" and "Porcupine" Moll., Proc. Zool. Soc. Lond., 1883, 

 p. 105, sp. 28. 



Station 75. July 2, 1873. Lat. 38° 38' N., long. 28° 28' 30" W. Off Fayal, Azores. 

 50, 90, and 450 fathoms. Volcanic mud. 



Habitat. — From the English Channel to the Canaries and the whole Mediterranean 

 basin from to 105 fathoms. 



Fossil. — From the Zanclean or lowest Pliocene of Sicily and Calabria onwards 

 (Seguenza). 



Chemnitz (loc. cit.) gives to this species a very few words of description beginning, it is true, 

 with the words " Trochus miuutus," but the reason for not following Dillwyn and Deshayes in adopting 

 that name is, that Chemnitz expressly says (what indeed is obvious) that he did not consider his 

 description of the species complete. I have, in spite of Dr. Fischer, quoted Chemnitz, f. 1 530, for 

 this species, because it exactly represents a very aberrant form which I dredged in Madeira, but 

 which certainly belongs to this species. 



This species is extremely abundant at Madeira. This species, Trochus zizyphinus, Venus casina, 

 and Venus ovata, all came to me under a label which bore " St. 75," but the depth marked on the 

 label was only 50 to 90 fathoms. 



Dr Gwyn Jeffreys has expressed in his British Conchology (loc. cit), and repeated with increased 

 conviction in his " Lightning " and " Porcupine " Moll. (loc. cit.), his doubts of the distinctness of this 

 species, from Trochus striatus, Linn. On a point such as this, lying in a field which Dr Gwyn Jeffreys has 

 so thoroughly made his own, the greatest deference is due to his opinion. At the same time, the very 

 great number of specimens, young and old of both species, which I collected in Madeira, the similarity 

 of their distribution, the absence of any connecting links between them, and the certainty with which 

 in all cases they can be distinguished, compel me to say that I am at a loss to imagine what grounds 

 there can be for an opinion which, I think, is held by Dr Gwyn Jeffreys alone. 



12. Trochus (Ziziphinus) similaris, Eeeve. 



Ziziphinus similaris, Reeve, Conch. Icon., vol. xiv. pi. v. fig. 32. 



„ „ Brazier, "Chevert" Moll., Proc. Linn. Soc. New South Wales, 1878, vol. ii. 



p. 44, No. 17. 



