ALASKA NEMERTEANS 



41 



can contract until the body becomes almost barrel-shaped. The worms 

 can neither swim nor roll up spirally. 



Proboscis. — Provided with a single, well-developed central stylet, 

 with a cartridge-shaped basis, and with two or more pouches of acces- 

 sory stylets. The proboscis sheath usually reaches nearly or quite to 

 the end of the body. 



Ocelli. — Usually present in very considerable numbers. A few 

 forms are without eyes, and a few others have but a single pair — there 

 are never 4. The eyes do not extend far behind the brain. 



Cerebral sense organs. — Usually well developed. Their position 

 is most commonly in front of the brain, but they are sometimes beside 

 or even behind the ganglia. 



13. AMPHIPORUS ANGULATUS (Fabr.)Verrill. 



pi. VI, fig. 4 ; p1. VII, figs. 2, 2a ; pi. xi, fig. 2 ; p1. xiii, fig. 3. 



Fasciola angiilata O. Fabricius, Muller's Verm. Terrest. et Fluv., i, p. 58, 



1774. 



Omatoplca stiinpsottu G\KAV.r>, in Stimpson, Invert, of Grand Manan, Smith- 

 sonian Contributions to Knowledge, p. 28, 1853. 



Nareda siiperba (?) Girard, loc. cit. 



Cosmoc ph da beringiana Stimpson, Proc. Acad. Nat. Sci. Philadelphia, p. 

 165, 1857. 



Amphiporus angulatits (Fabr.) Verrill, Marine Nemerteans of New Eng- 

 land, Trans. Conn. Acad., p, 10, 1892. 



"This large and conspicuous species is gen- 

 erally easily recognized by its clear dark purp- 

 lish or chocolate-brown color above, with pale 

 margins and a trapezoidal or triangular white 

 sjjot on each side of the head and usually with 

 a narrow white line across the neck ; and by the 

 pinkish or flesh-colored lower surface. Ocelli 

 in two or more rows in an elongated groove on 

 each antero-lateral margin of the head, and a 

 pair of small sub-dorsal clusters on the transverse 

 white nuchal band." (Verrill, loc. cit.) The 

 arrangement of the eyes and markings on the 

 head of the Alaska specimens are shown in fig. 

 10 and in p1. vi, fig. 4. In ordinary state of 

 contraction the body is rather short and stout. 

 When disturbed it can become so greatly thick- 

 ened anteriorly that its transverse diameter is fully J/3 as great as its 

 length. In extension the body is but moderately elongated, and is 

 relatively broad and flat. It contracts very much as does a leech. 



Fig. 10. Ampki- 

 portis angulatus. Dor- 

 sal view of anterior por- 

 tion of body showing 

 markings on the head 

 and the arrangement of 

 ocelli. X 8. 



