LIMAPONTIA. 257 



Placohranchus , Agassiz, Proc. Bost. Soc. Nat. Hist. iii. 19 (1850). 



Placobranchus catulus, Agassiz, MSS. 



1 Placuhranchus simplex, Girard, Proc. Bost. Soc. Nat. Hist. v. 89.(1854), no dcsci-i])tion.* 



Animal of a brownish sea-green color, with a whitish spot between 

 the tentacles, another running obliquely inwards and backwards 

 from the outer base of each tentacle half-way to the median line, a 

 small one at the tip of the alar expansion, and a larger one near the 

 margin of the expansion near its middle ; foot much paler, yellow- 

 ish green. Body ovate lanceolate, the lateral expansions about two 

 thirds its length and not quite meeting when reflected upon the 

 back. Head large, rounded in front, globose. Tentacles short, 

 broad, blunt, like cats' ears, so that the whole has a curious resem- 

 blance to the head of a kitten when viewed from above. Along the 

 back, as far as covered by the expansions, are fine longitudinal 

 folds. Foot nearly as wide as the body, squared in front, obtusely 

 pointed behind. Length, one fourth of an inch ; breadth, one tenth 

 of an inch. 



Found in the channel near East Boston, January, 1848 {Ag-assiz). 



Family LIMAPONTIID^. 



Body depressed. Tongue narrow ; teeth in a single central se- 

 ries. Tentacles none, or simple, contractile. Gills none external. 



In this group of slug-like forms the liranchial appendages are 

 altogether absent, or represented only by simple lobes or ridges on 

 the sides of the body ; the tentacles are linear, and not longitudi- 

 nally folded as in Elysiidcc, and the body is depressed. In the genus 

 Rhodope of Kolliker the Molluscan type appears to be at the low- 

 est stage of development, and to represent the Planarkc among the 

 Annelids. 



Genus L,IilIAP©T\TIA, Forbes. 1S32. 



Body depressed without lateral ridges. Head elevated at the 

 sides into crestlike ridges ; eyes large, sessile on the back of the 

 head, in the centre of pale circular spaces. Mantle distinct. 



* About a quarter of an inch lonjr, rather stout, bhint anteriorly, and tapering poste- 

 riorly, of a deep greenish hue ( Girard). 

 17 



