96 DORYMENIA ACUTA. 



difforentiated from the body proper, which posteriorly terminates in a very 

 pointed extremity as in Pronenmenia weberi Nierstr. The atrial opening is 

 relatively small, subterminal and surrounded by tumid lips which separate it 

 from the ventral furrow. As noted in a succeeding paragraph, the anterior 

 pedal gland is highly developed, but its outlet is not especially modified externally. 

 Posteriorly the pedal groove is continuous with the cloacal cavity. The cloacal 

 opening is relatively large, ventral and is overarched by the posterior pointed 

 end of the body, whose lateral margins are involuted, but may perhaps be flared 

 occasionally to expose the genital spicula, the appearance of the hinder end of 

 the animal resembling at such a time I chthyomenia ichthyodes Pruvot. 



A well-developed dorsal sense organ (Plate 15, fig. 11), visible in sections 

 only, is present a short distance from the posterior end of the body, and is sup- 

 plied with special nerves and blood sinuses as in P. Jiaicariensis. 



The cuticle investing the body is relatively thick (Plate 33, fig. 4), and is 

 developed by a hypodermal layer in which the component cells are of small size. 

 Those not instrumental in the formation of the spicules or papillae are more or 

 less cubical in form and consist of vacuolated cytoplasm in which the nucleus, 

 usually spherical, holds a central position. At various points the nuclei are 

 dense and elongated and may possibly belong to sensory cells. 



The spicules are hollow needle-like structures (Plate 37, fig. 10), those of 

 the alternate layers crossing the others almost at right angles. In their forma- 

 tion no points of especial interest appear. As usual several cells take part in 

 the process as in P. hawaiiensis. 



The papillae are of average number and present the appearance represented 

 (Plate 33, fig. 4). Three or four spindle-shaped nuclei occur in the slender 

 fibrous stalk while from five to seven are present in the swollen distal portion. 

 In this last named situation the nuclei are frequently of two sizes, small dense 

 bodies, and one or two of twice their size with a more vesicular appearance. 

 Judging from many sections both the number and character of these elements 

 are due to different stages in the development of the papillae. In advanced 

 stages these latter organs may open to the exterior and become so filled with 

 debris that the cellular elements save those of the stalk, become obliterated. 

 This, however, is undoubtedly an abnormal condition and marks the close of 

 an active functional existence on the part of the papilla. 



The anterior pedal gland, as in various other species of Neomeniina, is a 

 voluminous organ extending anteriorly as far as the brain, posteriorly as far as 

 the forward border of the radula and filling practically all of the space between 



