350 " THETIS " SCIENTIFIC KESULTS. 



Gastei'opods do these larval "Agadina" forms belong^ The marine 

 left-handed Gasteropods are not, indeed, very numerous. But it 

 must be remembered that some Gasteropods, vi^ith right-handed 

 spirals, have their initial portion or nucleus twisted to the left. 

 This is not improbably the case with the larval forms in question, 

 for the left-handed twisting of the operculum in all likelihood 

 corresponds to the right-handed twisting of the shell." 



A series of ^olariani showing the early stages, included in the 

 " Thetis " collection, has provided the solution of Pelseneer's 

 problem. 



The protoconch of S. maximum is white, smooth, sinistral, 

 turbinate, three-whorled, whorls slightly elevated, narrowly 

 umbilicated, with circular, expanded and reflected aperture. 

 With sudden change in colour, texture and sculpture, the adult 

 shell is built on the expanded lip. The protoconch is completely 

 inverted with regard to the adult, so that the larval umbilicus is 

 at the summit of the full grown shell, and the spire of the embryo 

 forms the centre of the umbilicus of the adult. The diameter of 

 the protoconch is about 1 '5 mm. 



My drawings show the basal aspect of a shell with half an adult 

 whorl, the umbilicus of which is forming round the embryonic 

 apex; also a slightly older shell viewed from above. 



Stripped of the adult shell, this protoconch conforms to the 

 figures and description given by Pelseneer of his '■'Agadina, n.sp." 



The larval shell of Solarimn appears to have been discovered 

 by Dr. Jousseaume, who described it at a meeting of the Societe 

 Zoologique de France.* For this type of apex Dautzenberg and 

 Fischer have proposed the term " anastrophic."f 



A few specimens were taken off Port Kembla in 63-75 fathoms, 

 off Cape Three Points in 41-50 fathoms, and off the Manning 

 River in 22 fathoms. 



SOLARIUM STRAMINEUM, Gmelin, sp. 



Trochus stramineus, Gmelin, Syst, Nat. xiii., 1790, p. 3575. 



Solarium stramineum, Hanley, Thes. Conch., iii., 1863, p. 242, 

 pi. v., f. 95, 96, 97. 



Stations 37, 49. 



A few young shells were taken off Port Kembla in 63-75 

 fathoms, and off Botany Bay in 50-52 fathoms. 



* Jousseaume — Bull. Soc. Zool. France, vii., 1882. Proces Veibaux, p. xxx. 

 t Dautzenberg and Fischer— MtJm. Soc. Zool. France, ix., 1896, p. 57. 



