334 NOTES ON PROSOBRANCHIATA, IV., 



merely the first appearance of the adult sculpture, whether 

 accompanied or not by differences of contour; (2) the presence in 

 one and absence from the other of some such bizarre feature as the 

 sinuation and claw-like processes of Purpura protoconchs; and 

 (3) a completely different axis of coiling in the two, as between 

 Tripliora and Turhonilla. Such, however, will most probably be 

 found to be correlated with differences, of equal or greater 

 importance, in shell or anatom3^ 



The conclusions of this section are that the protoconch is to be 

 used in conjunction with other features, and that only where the 

 other features, anatomic or conchological, are negative or unknown 

 is it to be used in deciding a systematic position or generic 

 segregation. It will often be found useful as an indicator of 

 deeper seated differential characters otherwise unsuspected. 



Just as this goes to press the Journal de Conchyliologie for 

 May, 1905, has come to hand; in this number is an abstract by 

 G. D(ollfus) of a review by Dr. Boettger of a recent paper from 

 the pen of Grabau; the original of this review is not available to 

 me, but as the writer's conclusions are very pertinent to the 

 present discussion, I give the following free translation of the 

 abstract — Dr. Boettger is of opinion that 7io iveighty conclu- 

 sions can he based on ' Heterostylie,^ that is to say, on the 

 difference in the course of growth of the spire of Gastropod 

 shells; he recalls the fact that Sturany in the expedition of the 

 ' Pola ' found very different embryos for 3Iurex trihuliis, and for 

 Fasics hifrons, according to the situation whence they were 

 collected, and that they were always larger when he collected 

 these species in great depths than when he collected them in 

 coastal regions. It seems, indeed, that the embryos of a single 

 species are able to undergo a kind of adaptation, and that this 

 differential character, far from recalling an ancestral form^ 

 appears as an ' accommodation ' entirely secondary. 



