536 POSITION OF PURPURA TRITONIFORMIS OF BLAINVILLF, 



and proposed the suborder Brachiocephala for the reception of the 

 family. In the first volume of their "Genera of Recent MoUusca" 

 (p. 60, 1853), the brothers Adams placed the genus Sinusigera 

 among the Pteropoda, but in the second volume (1858, p. 613) as 

 a result of Dr. Macdonald's article they placed it among the 

 Heteropoda in their family Macgilliv7'ayidce. 



The first to realise that Sinusigera was an embryonic and not 

 an adult mollusc was Dr. J. D. Macdonald,"^ in 1858, and he gave 

 his reasons for supposing one he had found to be the pullus of a 

 Pedicularia. 



As the apex of the Pedicularia he figured shows at least two 

 smooth and three cancellated whorls, and the pullus shows only 

 one cancellated whorl, and as there is also a difference of contour, 

 we may be allowed to doubt the correctness of his conclusions 

 till further proof is forthcoming. Dautzenbergf figures the apex 

 of a Pedicularia, but he does not mention any Sinusigera-characters. 

 Further, it might be well to notice that Macdonald's pullus, which 

 is very similar to the one I figure, came from about the same 

 locality. 



This note of Macdonald's, although it sowed the seeds of doubt, 

 did not settle the matter conclusively, for A. Adams described 

 several subsequent to its appearance, and Craven's monograph, in 

 which he described new species, was published in 1877. The 

 latter considered the constancy of shape and size of each species 

 proof of the stability of the genus, 



Jousseaume,t in a " iSTote sur le developpement des coquilles," 

 says that Mons. Calamle, of Benguela, had found that the embry- 

 onic whorls of P. hcemastorna, Linn., show all the characters of a 

 Sinusigera. Craven§ figures a young stage in the growth of a 

 Purpura showing the Sinusigera-character of the pullus; this he 

 believes is P. hcemastoma, and remarks that the pullus is very 

 similar to S. cancellata, D'Orb. Crosse|| republished his figures, 



* Trans. Linn. Soc. Lond. Vol. xxii. p. 241. 



t Result. Camp. Scien. de Prince de Monaco. Fasc. i., pi. iv., figs. 2a-2h. 



\ Le Naturaliste, 1882, p. 183. 



§ Ann. Mag. Nat, Hist. 1883, p. 141. 



II Journ. de Conch. 1885, p. 161, pi. ix., fig. 5. 



