Mr. W. Clark on the genus Lepton. 133 



cies, and contrary to L. squamosum, the longer and broader end 

 is anterior, but the beaks are so central, that there is little dif- 

 ference in the sides ; the single sessile anal tube is exactly as in 

 the last species ; there is no branchial siphon, — the water enters 

 at the extensive ventral aperture. The foot is almost in every 

 respect similar to that of its congener ; it is perhaps larger in 

 proportion, of pale azure hue, marked with intense but irregular 

 flake-white minute blotches ; the posterior extremity is as long 

 as the portion anterior to the pedicle; its termination is per- 

 fectly aciculate, and like its congener deeply grooved as far 

 as the junction with the body, at which point is the byssal 

 gland, and the superabundant filamentous matter is similarly 

 discharged. 



The L. squamosum is a lively creature, but this, not one-third 

 of the size, is far more active, creeping up a glass as easily as a 

 Gasteropod ; but the posterior portion of the foot is not expanded ; 

 perhaps in freedom it is deployed on the march ; in confinement 

 both shell and foot are carried laterally. The liver is light 

 green, united to a flake-white ovarium, now, in June, full of ova. 

 Transverse length ^, vertical y^^ diameter yj of an inch. It 

 would appear that this species in every essential is identical with 

 the L. squamosum, and it settles the position of the yet undis- 

 covered L. convexum. This is the first record of this rare animal 

 that has appeared. 



Exmouth, June 20, 1852. 



I have this day the pleasure to state, that the problem is solved 

 as to the identity or distinctness of the Lepton nitidum and 

 L. convexum by the capture of a live specimen of the latter, 

 having the shell sculptured with the rough and intensely marked 

 characteristic punctures of that species. On putting the animal 

 into water it instantly deployed its organs ; and for their descrip- 

 tion I have only to refer to the preceding account of the L. niti- 

 dum, which in future will take the appellation of a variety of its 

 old associate. The two are so identical, that after ten days^ exa- 

 mination I can make no alteration in the minutes, except the 

 having seen the animal march on the disk of the foot, more than 

 once, with the shell in a vertical position ; it has all the same 

 habitudes as the L. squamosum, and of course differs in no re- 

 spect from its smoother variety, the late L. nitidum. It is now 

 alive, and probably by changing the water daily it will live as 

 long or longer than the L. squamosum mentioned above. It is 

 therefore evident that the punctures of this species are very 

 variable, ranging from the most minute granules that scarcely 

 interrupt its smoothness to the coarsest sculpture. 



As the specific appellation of nitidum is obviously improper, 

 the more significant one of convexum ought now to be adopted. 



