PHYLLAPLYSIA. 133 



laterals broad and blunt. The position of the genital pore is not 

 given by Fischer. 



In habits Phyllaplysia is like Petalifera and Notarchus, living on 

 Zostera and other sea-weeds upon which they feed, clinging with 

 limpet-like tenacity to the supporting surface, and mating recipro- 

 cally like the land snails. 



P. LAFONTI Fischer. PL 36, figs. 1,2; pi. 9, fig. 26. 



Length 15-35 mill. Body very much flattened, rounded in front, 

 obtuse behind ; head and neck short. Anterior tentacles wide, flat- 

 tened, confluent at base, hollow, slit in front, truncated at the apices ; 

 rhinophores hollow, dilated at the ends, slit; the eyes in front of 

 them. Branchial slit small, covered by small lobes ; foot very 

 wide, subtruncate in front ; buccal processes conic and transverse. 



Color pale green above, ornamented with concentric zones of a 

 darker green, and small scattered spots formed of a rounded white 

 dot surrounded by violaceous punctation, these spots appearing also 

 on the anterior tentacles and becoming tubercular there ; upper 

 tentacles pale green, with 4 or 5 rings of pale violet. Foot very 

 light greenish- white; buccal processes white and transparent. 



Shell wanting. 



Basin of Arcachon, s. w. France, on sea- weeds. 



Dolabrifera lafonti Fischer, Ann. Sc. Nat. (5), xiii, 1870, p. 3 (no 

 description). Phyllaplysia lafonti FISCHER, Journal de Conchy]., 

 1872, p. 297, pi. 15, f. 1-3 ; Actes Soc. Linn. Bord., xxix, 1873, p. 

 236. CROSSE, Journ. de Conch., 1875, p. 101. 



This species lives on Zostera, which it resembles in color. They 

 adhere strongly by the large foot, and crawl rapidly like Limaces ; 

 sometimes they float foot upward at the surface, in the manner of 

 Limnseidse. They cannot, of course, swim like Aplysias. Copula- 

 tion is reciprocal, as in the Helices, two individuals placing them- 

 selves side by side, the head of one toward the tail of the other. 

 They have been found only in the locality named and during the 

 month of September. 



Crosse collected a specimen 35 mill, long, 9 broad, in which the 

 concentric zones and the spots were less conspicuous than in the 

 types, the general color being a more vivid green. The animal, as 

 observed by him in an aquarium, is habitually longer than shown in 

 Fischer's figure, especially when in motion. The dorsal bands are 

 more numerous and less distinctly concentric than shown in the 



