THE NAUTILUS. 



133 



Dr. Gould's description agrees perfectly with his figure. 

 Both text and figure prove that his Placobranchus was a true 

 Elysia with lateral lobes not united dorsally. He says: 

 "Body ovate-lanceolate, the lateral expansions about two- 

 thirds its length and not quite meeting when reflected upon 

 the back. ' ' 



The species will stand thus : 



Genus Elysiella Verrill, 1872 : type 

 Elysiella catula Verrill, 1872. 

 Elysiella pusilla Bergh, 1872. 



Genus Elysia : Elysia catula Gould (Placobranchus catulus 

 Gould, 1870). 



HELIX NEMORALIS AT KNOXVILLE. TENNESSEE. 



BY T. D. A. COCKERELL. 



Mr. M. D. Barber has very kindly sent me a series of H. 

 nemoralis collected at Knoxville; descendants of the Lexing- 

 ton, Va., colony, as explained by him in Nautilus, xxxi, p. 

 107. The specimens all have the yellow ground color (var. 

 libellula), and sort out as follows: 



Adults. 



00000. 16, four of which are bimarginate (the dark peri- 

 stome bordered inwardly with a white rib). 



10345. 2, one having max. diam. 26 mm. 



12345. 21, of which five are bimarginate. 



123(45). 14, of which two are bimarginate; two have max. 

 diam. 25 mm. 



123 4 45. one. 



Immature. 



00000. 16. 



12345. 15. Some would doubtless have become 123(45) 

 on maturity, the formula being taken from 

 near the mouth. 



123 ( 45 ) . six ( var. reaumuria Moq. ) . 



(12)3(45). three. 



10345. two (var. argenvillea Moq.). 



