10 NEW-YORK FAUNA — MOLLUSCA. 



EOLIDIA DIVERSA. 



PLATE V. FIG. 97. 

 E, diverm. Couthouy, Bost. Jour. Nat. Hist. Vol. 2, p. 187, pi. 4, fig. 14. 



Description. Body elongated, acute behind. Head distinct, sub-orbicular, depressed, with 

 two long slender lateral tentacula arising from near its junction with the neck ; two round and 

 smooth shorter ones on the back of the head, a little behind the others. Eyes minute, just 

 behind the latter pair. Branchial cirri disposed in a double series along the back. Sexual 

 orifice large, just behind the neck on the right side ; vent a short distance behind and below 

 it. Foot divided at its origin, forming two processes. 



Color. Semitransparent pale yellow, tinged with red. Branchial cirri internally orange. 



Length, 1*2. Breadth, 0-35. 



Found near the roots of Lancinaria saccharina, on the coast of Massachusetts. 



EOLIDIA GYMNOTA. 



PLATE V. FIG. 95. —(CABINET OF THE LYCEUM.) 

 Eolis ( Tergipes) gymnota. Couthouy, Bost. Journ. Vol. 2. p. 69, pi. 1, fig. 3. 



Description. Body elongated, slender, tapering gradually to the tail. Neck very distinct. 

 Head short, depressed, orbicular, perpendicularly linear. Tentacula four : the lower pair 

 round, smooth on the front of the head, and an eighth of an inch long ; the other pair rather 

 shorter, serrated, and on the back of the head. Gills disposed in seven remote clusters along 

 the sides ; the medial longest. Back with a central elevation. Sexual organs on the right 

 side, below the first group of branchiae. Vent on the same side, higher up, and between the 

 third and fourth group of branchias. 



Color of the gills reddish brown. Foot transparent. 



Length, 0-9. 



The animals of this section are very varied in form, and our acquaintance with them is 

 but of modern date. I place provisionally here an inhabitant of our salt water which I have 

 nowhere seen described, and which was sent to me under the name of Aquatic larva, from 

 the Hudson river, a short distance above the city. 



