28 ]\Ii'. W. Clark on the Lepton sulcatulum. 



In the 'Aunals of Natural History/ 3rcl series, vol. iii. p. 406, 

 I submitted some observations on Mr. JefFreys's " Gleanings in 

 British Couchology," in one of which (in the series, and page 31' 

 of the vol. above quoted) that gentleman has introduced a new 

 species termed Lepton sulcatulum, illustrated by PI. 11. fig. 2 a-g, 

 and on which, in the same vol., p. 409, I have stated amongst 

 my remarks, that " Lepton sulcatulum appears to be a good spe- 

 cies — that is, on shell examination.'^ 



This conjecture has not been verified, as I think I shall prove 

 that no such species exists; my opinion was based on the 

 examination, as I thought, of a perfect shell. I was misled by 

 the specimens sent me by Mr. Jeffi'eys, which proved imperfect 

 in having a portion of the primary denticular processes broken 

 away; and in consequence the point within the beaks appeared 

 to present a fovea or pit indicative of an internal ligament, and 

 the shell had thus an approach to the hinge of a Lepton. I 

 received only one entire example, which could not be safely 

 opened, and four separate valves. The matter has rested here 

 for some months; but having been, only last week, very un- 

 expectedly favoured by the Rev. Alfred Norman with perfect 

 closed and open examples of the Lepton sulcatulum of Jefi^reys 

 from Jersey or Guernsey, and also having had, within these few 

 days, the whole of Mr. Norman's stock of that supposed species 

 forwarded to Bath for my inspection, I am enabled to say, aided 

 by two fine live specimens which I fortunately have just dis- 

 covered in my cabinet, that they do not represent a new species 

 of Lepton. 



These minute objects are the fry of the well-known Circe 

 minima. I have rigorously compared them with many sizes of 

 that species. Four excellent open pairs of these very young 

 shells show the precise dentition of Circe ; the ligament, as in 

 it, is short, linear, and essentially external, though it is in a 

 great measure obscured from view by running within the com- 

 missure of the two valves; the pallial impression, as in that 

 species, is almost without a posterior sinus (indeed it is scarcely 

 indented), and proves that the tubes of the animal are short, 

 and that it is closely allied to Cijprina and Astarte ; the cordi- 

 form impression under the beaks even of these Circjcan pigmies 

 is very visible in fresh examples, but in the worn and imperfect 

 shells usually seen in collections it is hardly discoverable; in 

 adults it is not very strongly marked. 



If the dentition of these minute phases of Circe is placed un- 

 der the microscope, in comparison with the accredited Leptons 

 (of which we have only three species), the discrepancy of the two 

 will be apparent. The former {Circe), luuler adequate optical 

 assistance, which should not be less than the half-inch object- 



