28 PHILINID^E. 



Renier ; and the Doridium membrartaceum, of Meckel, 

 or D. Meckelii, of Chiaje, is the Aglaia tricolorata of 

 Renier. The new species we have figured was discovered 

 by Mr. Gould in Australia. 



Sjyecies of Aglaia. 



depicta, Renier. tricolorata, Renier. 



lineolata, H. and A. Adams. 



Genus POSTEROBRANCHiEA, D'Orbigny. 



Cephalic disk transverse, dilated at the sides ; eyes 

 none. Mantle large, extending beyond the foot, except 

 posteriorly ; gill on the left side of the body. Foot 

 divided into two parts by a deep, transverse groove ; the 

 hind part longitudinally fissured and divided into two 

 lobes. 



Shell none. 



Syn. Posteobranchus, D'Orb. (olim). Posteriobran- 

 chus, Gray. 



Ex. P. maculata, D'Orbigny, pi. 58, fig. 5, 5, a. 



As in Aglaia and other genera belonging to this group, 

 the tentacles are confounded with the large, persistent, 

 frontal veil, forming a fleshy cephalic disk or frontal lobe; 

 the present genus seems to differ from all the others of the 

 family, in the branchial plume being situated on the left 

 side. The genus has greater affinities with Aglaia than 

 with Pleurobranchus, near which its author considered it 

 should be placed ; it was discovered by M. D'Orbigny, 

 crawling on the muddy sand-flats of the shores of South 

 America, and has the same habits, and lives at the same 

 depths as Aplysia. 



