CHAETODERMA CAUDATUM. 193 



NIERSTRASSIA, gen. nov. 



Body short, 2.5-5 mm. in length by 0.75-1 mm. thick. Single layer of 

 leaf-like keeled spines as in Chaetoderma; no papillae. Epithelium of atrium (?) 

 composed of long, slender cells without cirri and ciliated ridges. Radula dis- 

 tichous, 15 transverse rows. Dorsal salivary glands diffuse, ventral small, 

 lobulated. Coelomoducts with three pairs of diverticula, two bundles of copu- 

 latory spines (5 in each bundle) opening into terminal part of shell gland. Repro- 

 ductive opening on large papilla. Posterior walls of cloaca with 5-6 glandular 

 folds. Type of genus N. fragile, sp. nov. with characters of the genus. Off 

 New Jersey coast, 479 fms. (p. 235). 



DESCRIPTION OF SPECIES. 



Chaetoderma nitidulum Loven. 



This species is represented by over fifty specimens dredged from various 

 comparatively shallow water stations between Newfoundland on the north 

 to Virginia on the south. Whether this last named locality represents the 

 southernmost limit of distribution it is impossible to state as the work of explora- 

 tion south of 37° north latitude is largely confined to deep water. In the present 

 case the bathymetrical distribution ranges from 25 to 300 fathoms; elsewhere it 

 is reported to range from 25 to 2,250 meters. Specimens in the present collec- 

 tion have been taken at the stations noted on page 183. 



A careful comparison of these western Atlantic specimens with the descrip- 

 tions given by various authors and with a single individual from the Kara Sea 

 discloses no essential differences. One of the Atlantic specimens is unique in 

 being monocious. Throughout its entire extent the gonad is distended with 

 vast numbers of spermatozoa, mature and in various stages of development. 

 The ova are also in different stages of growth, and roughly speaking are developed 

 on the surface of an inconspicuous septum separating the halves of the ovo- 

 testis, while the sperms arise from more lateral positions. 



Chaetoderma caudatum, sp. nov. 



Eight specimens of this species were dredged off the coast of New Jersey 

 (Sta. 2588A) in 479 fathoms of water where the bottom consisted of green mud. 

 In every case the posterior end of the body rapidly narrows in the vicinity of 

 the cloaca to form a tail-like appendage of approximately even calibre through- 



