CLASSIFICATION. 43 



Chaetoderma Loven, 1845. 



Body vermiform, without ventral groove; mouth and anal chamber ter- 

 minal. Two gills. Sexes separate. Radula reduced to conical peg. Type of 

 genus C. nitidulum. 

 C. aryentea, sp. nov. 



Length 24 mm. by 1.6 and 2.6 mm. through the metathorax and preabdomen 

 respectively. Silvery white. Spines, in side view, usually bent. Alaska. 

 (p. 62.) , 



C. attenuata, sp. nov. 



Body long and slender, measuring 61 mm. in length by 1.5 through the 

 metathorax and 2.7 through the preabdomen. Buccal plate relatively small. 

 Alaska, (p. 55.) 

 C. californica, sp. nov. 



Body measuring 24 mm. in length by 1.6 mm. greatest diameter. Larger 

 spines with expanded bases. California, (p. 64.) 

 C. erudita, sp. nov. 



Average length, in preserved state, 27 mm. by 2.5 mm. average thickness 

 of preabdomen. Buccal plate deeply cleft by mouth opening. Brain of large 

 .size. Alaska, (p. 59.) 



C. hawaiiensis, sp. nov. 



Body slender, measuring 12-19 mm. in length by 0.5-0.6 mm. greatest 

 thickness. Buccal plate broadly elliptical, perforated in centre by mouth. 

 Hawaii, (p. 49.) 

 C. japonica, sp. nov. 



Length 17 mm. by 1.5 mm. greatest thickness, buccal plate shield-shape, 

 perforated by mouth opening. Japan, (p. 67.) 



C. moiitereyensis, sp. nov. 



Length 45 mm. by 3 mm. greatest diameter. Buccal plate unusually 

 large. Tooth stout. Monterey Bay, California, (p. 61.) 



C. nanula, sp. nov. 



Body small, comparatively stout, measuring 9 mm. in length by 1.4 mm. 

 greatest diameter. Spines keeled and of heavy appearance. California, 

 (p. 66.) 

 C. robusfa, sp. nov. 



Body heavy, measuring 60 mm. long by 3.5 and 4.7 mm. through the meta- 



