42 COE 



The Alaska specimens are commonly larger than have been recorded 

 elsewhere, often measuring 200 mm. or more in length and 10 mm. in 

 width. 



Proboscis. — The proboscis is large, thick, and pale reddish or 

 salmon in color. The smallest specimen collected had 17 nerves in 

 the proboscis; four other specimens examined had each 18 probos- 

 cidial nerves, one had 19 nerves, and two others had 20 each.^ This 

 shows more strikingly than has previously been pointed out that the 

 number of nerves in the proboscis is variable to a very considerable ex- 

 tent. Burger ^ has shown that Drepanoporus crassus may have 19 or 

 20 nerves, and D. spectabilis 24 or 26. Nevertheless in the other 

 Alaska species the number has been found surprisingly constant. The 

 number of nerves in any particular proboscis remains perfectly con- 

 stant so far as I have observed from the anterior end back as far as the 

 stylet region. Here they break up into a plexus and lose their iden- 

 tity. The nerves in A. a7ignlatus enter the proboscis at its anterior 

 attachment and in its ventral portion (p1. xi, fig. 2). They then 

 divide into their definite number of branches (usually 18) which pass 

 obliquely dorsally and arrange themselves symmetrically on the periph- 

 ery. The proboscis sheath extends within a few sections of the pos- 

 terior end of the body. 



The armature of the proboscis is made up of a moderately slender 

 central stylet, and (usually) two pouches of accessory stylets. The 

 basis of the central stylet is about as long as the stylet itself. It is 

 moderately slender, constricted near its middle (p1. vii, figs. 2, 2a), 

 enlarged and rounded posteriorly. Each reserve pouch commonly 

 contains 5 to 7 rather slender stylets, similar in size and shape to the 

 central stylet. 



Ocelli. — Numerous and characteristic in arrangement. The dark 

 pigment on the head, however, often renders them difficult of accurate 

 determination. Girard* states for Omatoplea stimpsonii that there are 

 six or more minute eyes " situated in an oblique, simple row, on either 

 side of the head anteriorly." The same author (loc. cit.) describes 



*Of eight specimens of this species from Eastport, Maine, one had but 17 

 nerves in the proboscis, six had 18 each, and one had 19 or 20. Other anatom- 

 ical details in the eastern form agree perfectly with those of specimens from 

 Alaska. I have recently examined a number from the original locality of Stimp- 

 son's C. beringiana (Bering Strait), and have no doubt as to the specific identity 

 of this form with that from southern Alaska and from Eastport, Maine. 



^ Fauna u. Flora des Golfes von Neapel. Monogr. 22, Nemertinen, p. 372, 

 1895. 



'Marine Invert. Grand Manan, Smithsonian Contr. to Knowledge, p. 28, 1853. 



