10 H. F. NIERSTRASZ. 



ones, considering in the first place the exact structure of the radula and salivary 

 glands. I propose the following division : 



FAMILY PRONEOMENIIDAE. 



Index at least 6. Cuticle thick, with many layers of spicules, by far the greater part of which is 

 pointed and hollow. Epidermal papillae present. One or more dorso-terminal sense-organs. Radula and 

 salivary glands present. Gills are wanting. 



A. Radula multiserial. Salivary glands tube- or bag-shaped. 



Proneomenia Hubrecht. 



a. Radula with basal membrane. Salivary glands tube-shaped, uniting before opening 



out into the digestive tract. Receptacula seminis strongly folded, glandular. The 

 spicules remain connected with the epidermis by multinuclear stems. Abdominal 

 spicules present. Index 9-14. 



Proneomenia sluiteri Hubr. (4.) 

 (= langi Heuscher), 



Barent's Sea, Spitzbergen. 

 70-160 fathoms. 



b. Radula with basal membrane. Salivary glands tube-shaped, opening out separately. 



Receptacula seminis vesicular or tube-shaped. 



a. With abdominal 'and cloacal spicules. Receptacula seminis vesicular. 

 One dorso-terminal sense-organ. Index 22-50. 



Proneomenia weberi Nierstr. (6, p. 2.) 



East-Indian Archipelago, 22-1633 M. 

 Proneomenia longa Nierstr. (6, p. 7.) 



Saleyer, East Indian Archipelago, 1158 M. 



ft. Without abdominal, with cloacal spicules. Receptacula seminis vesicular. 

 Two dorso-terminal sense-organs. Index 10. 



Proneomenia discoveryi Nierstr. 



77 50' 80" S., 165 40' 5" E. 100 fathoms. 



y. Without abdominal or cloacal spicules. One dorso-terminnl sense-organ. 

 Receptacula seminis vesicular or tube-shaped. Index 9-18 '5. 

 Proneomenia valdiviae Thiele (16.) 

 3 7' S., 40 45' 8" E. 748 M. 

 Proneomenia oxuminata Wircn (18, p. 68.) 



West India. 300 fathoms. 

 Proneomenia hawaiemis Heath (1.) 

 (? insufficiently known.) 



Hawaian Islands. 



Proneomenia gerlachei Pels. (10, p. 16.) 

 70 S., 80 48' W. 500 M. 



c. Radula without basal membrane. Salivary glands tube- or bag-shaped, opening out 



separately. Receptacula seminis vesicular. 



a. With abdominal and cloacal spicules. Salivary glands tube-shaped. 

 1-3 dorso-terminal sense-organs. Index 6. 



Proneomenia vagans Kow. a. Mar. (5, p. 29.) 



Mediterranean. 



/3. With abdominal, without cloacal spicnles. Salivary glands bag-shaped. 

 Receptacula seminis numerous, often lobate. One dorso-terminal sense- 

 organ. Index 11. 



Proneomenia thulensis Thiele (14.) 

 80 8' N., 16 55' E. 480 M. 



