90 DOUVMENIA ACITA. 



differentiated from the body proper, wliieh ]iosteriorly terminates in a very 

 ])(>iiited extremity as in I'roucdnienia webcri Nierstr. The atrial opening is 

 rehxtively small, subterminal and surrounded by tumid lips whieh separate it 

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

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

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

 opening is relatively large, venti'al and is overarched liy the posterior ])ointed 

 end of th(> body, whose lateral margins are involuted, but may perhaps be flared 

 occasionally to expose the genital s])icula, the appearance of the hinder end of 

 the animal resembling at such a time Iclilhyonienia ichthyodes Pruvot. 



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

 only, is ])resent a short distance from the posterior end of the body, and is sup- 

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



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

 developed })y a hypodermal layer in which the component cells are of small size. 

 Those not instrumental in the formation of the spicules or pa])illae are more or 

 less cubical in form antl consist of vacuf)lated cytoplasm in which the luicleus, 

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

 tlense 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 antl present the aj^pearance represented 

 (Plate 33, fig. 4). Three or four s])indle-shai)ed nuclei occur in the slender 

 fibrous stalk while from five to seven are present in the swolhni distal jioi-tion. 

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

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

 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 ]iart 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 jiractically all of the space between 



