2o8 BULLETIN: MUSEUM OF COMPARATIVE ZOOLOGY. 



caecum is stated by GriiRn ('98, p. 214) to be wanting. A species 

 from the Arctic Ocean (A. tnacr acanthi is) can be readily distin- 

 guished from all other known species of the genus by the com})ara- 

 tively enormous size of the basis of the central stylet — the basis 

 alone measuring about a millimeter in length or one eighteenth the 

 total length of the body of the worm when contracted. And, 

 finally, a single species {A. gelatinosus) from a depth of 159 fms. is 

 remarkably gelatinous and probably somewhat hyaline in life, and 

 is well suited for an existence at a considerable depth of water. 



It is hoped that in the near future further collections will furnish 

 a sufficient number of well preserved specimens of those species 

 which are still imperfectly known anatomically, because of the 

 absence of the proboscis or for other reason, so that the conspicuous 

 gaps in even this small com])arative table may be tilled up, and a 

 complete table containing a much wider range of characters may be 

 possible. 



53. Amphiporus angulatus (Fabr.) Verrill. 



Fasciola augulata O. Fabricius, Miiller's Verm. Terrest. et Fluv., 1, 



p. 58, 1774. 

 Omatoplea stimpsonii Gu'ard, in Stimpson, Invert, of Grand Manan, 



Smithsonian Contributions to Knowledge, 6, p. 28, 1858. 

 Cosmocephala heringiana Stimpson, Proc. Phil. Acad., p. 165, 



1857. 

 Amphij^orus angulatus (Fabr.) Verrill, Trans. Conn. Acad., 8, p. 



390, 1892. 

 Amphiporus angulatus Coe, Proc. Wash. Acad. Sci., 3, p. 41, PI. 



6, %. 4; PI. 7, %. 2 ; PI. 11, fig. 2 ; PI. 13, fig. 3, 1901 ; Ilar- 



riman Alaska Expedition, 11, p. 41, 1904. 



PI. 1, figs. 5, 6 ; Text-figs. 19, 46, 47. 



This common and widely distributed species may be recognized 

 by the following brief diagnosis : — Body of large size, short, stout 

 and flattened in ordinary states of contraction. When disturljed 

 the worms can become so greatly thickened anteriorly that the 

 transverse diameter in this region is nearly one third as great as the 

 length of the body. Length up to 20 cm. or more; width some- 

 times 10 mm., although most individuals are less than half these 



