smith: on the genus astarte. 199 



shell. Again other species (e.g., A. eliiptica, A. fabula and 

 A. compressa) are more or less ribbed yet always have smooth 



edges. 



The result of my own observation upon this point coincides 

 with the opinion expressed by Gould and Searles Wood, that in 

 such species as have notched margins the crenulation is a mark 

 of maturity. If it be not, how is it that we never find it in small 

 and what appear half-grown shells, and always in those which are 

 evidently very old. 1 have seen a great many specimens of 

 A. sulcata, and on opening those which on account of the 

 thickened margins of the valves I deemed adult, only in one 

 instance have I been somewhat deceived. '1 his particular shell 

 exteriorly exhibited all the aspect of maturity, yet on parting the 

 valves the margins seemed smooth. On a closer scrutiny 

 however, I could certainly detect traces of incipient crenules. 

 Who can say that this shell, had it been permitted to live a short 

 time longer, would not have developed the crenulations? In my 

 opinion such would have resulted. Jeffreys in the second volume 

 of the "British Conchology," p. 310, says — "I have adult speci- 

 mens of A. sulcata with the margin quite plain and smooth in 

 front, but distinctly notched on each side." 



Here is in my opinion a further instance where the specimen 

 appears to have almost arrived at maturity (for I dispute the 

 assertion of its adultness), and consequently has partially com- 

 pleted the crenulation of the margin. There are also specimens 

 of the same species in the British Museum in which the 

 crenulation is indicated on the lateral edges only, so it would 

 appear that the animal produces this feature first of all at that 

 particular part. 



The principal writers upon the recent species of Astarte are 

 Hanley in his "Catalogue of recent bivalves," pp. 87, 88 and 

 350; Philippi in his "Abbildungen und Eeschreibungen neuer 



