PROCEEDINGS OF UNITED STATES NATIONAL MUSEUM. 339 ' 



The verge is armed witli small hooks, but the spicule, present in the 

 latter genus, is not protruded in any of our specimens of Koonsia, if 

 present. 



Koonsia obesa Verrill. 



Trans. Couii. Acad., v, p. 545, July, 1882. 



Body large, stout, broad, with a large swollen back, smooth and white 

 in the preserved specimeus, and defined by the mantle-edge, which 

 forms a rim along the lateral and posterior borders. Head large and 

 broad, with two short, fiat, posteriorly grooved, anterior tentacles, one 

 at each corner; the anterior mantle-border runs between them, and sup- 

 ports a row of small papilla?. Posterior tentacles short, stout, flat- 

 tened, ear-like, with the outer edges incurved, forming a large groove. 



Foot broad and rounded anteriorly, with small auricles ; long, tapered 

 and acute posteriorly, extending some distance beyond the mantle; a 

 conical papilla, near the tip, above; under side, near the end, with a 

 narrow, elongated, depressed, glandular area, surrounded by a raised 

 border; this is sometimes tinged with bright red, in alcohol; the rest 

 of the foot is usually tinged with chocolate-brown. 



Gill large, bipinnate, deep purple. 



This species grows to a great size. One, from station 939, was over 

 5 inches (128'"™) long; 4 inches (102""") wide; and about 2 inches (50"^™) 

 high, even after preservation in alcohol. 



Ofl" Martha's Vineyard, stations 895, 939, 940, 1025, in 210 to 258 fath- 

 oms. Oft" Delaware Bay, station 1015, in 312 fathoms. At station 946, 

 in 241 fathoms, seven young specimens were taken, some of them not 

 over 1 inch long ; these were associated with Fleurobranchcm tarda. 



This genus is dedicated to Mr. B. F. Koons, of the U. S. Fish Com- 

 mission, in 1880 and 1881. 



NUDIBEANCHIATA. 



Issa ramosa Verrill and Emerton. 



Verrill, Amer. Jouru. Sci., xxii, p. 301, 1881; Trans. Conn. Acad., v, p. 547, 

 pi. 58, figs. 3G, 36 rt. 

 Stations 940 and 949, in 130 and 100 fathoms. 



Heterodoris robusta Verrill & Emerton. 



Ileterodoris rohusta Verrill and Emerton, Verrill, Trans. Conn. Acad., v, p. 

 549, pi. 58, figs. 35, 35«, 35Z». 

 Oft" Martha's Vineyard, station 1029, in 458 fathoms. 



Dendronotus arborescens Alder & Hancock. 



Verrill, Proc. Nat. Mus., iii, p. 385, 1880. 

 Station 1038, in 140 fathoms, 1881; several specimens. 



Fiona nobilis Alder & Hancock. 



Verrill, Amer. Journ. Sci., xxii, p. 301, 1881. 



Abundant at stations 935, 995, among Anatifers, adhering to pieces of 

 floating timber. 



