146 



form, which was unknown to Prof. Brady, as also the form named by Boeck 

 Diosaccus abyssi, belongs to the genus Amphiascus, recently established by the pre- 

 sent author. The genus Diosaccus, in the restriction here adopted, differs con- 

 spicuously from the other 2 genera included in the present family, both in 

 external appearance and in several of the anatomical characters. In addition to 

 the typical form, another nearly-allied, though evidently distinct species has been 

 described by Th. Scott as Diosaccus propinqvus. Only the type species has as yet 

 been found off the Norwegian coast. 



92. Diosaeeus tenuicornis (Glaus). 



(PI. LXXXIX & XC). 

 Dactylopus tenuicornis, Claus, Die freilebenden Copepoden, p. 127, PI. XVI, figs. 17 23. 



Specific Characters. Female. Body moderately robust, with the anterior 

 division considerably broader than the posterior. Cephalic segment more than 

 twice as long as all the free segments of metasome combined, and evenly vaulted 

 above ; epimeral parts very fully developed and much curved in the middle, 

 embracing between them the oral parts, only the posterior maxillipeds projecting 

 beyond their edges. Kostrum somewhat lamellar and very prominent, being 

 slightly curved. Epimeral plates of the 3 succeeding segments of moderate size, 

 deflexed and angular behind. Last segment of metasome narrower than the pre- 

 ceding ones, and without distinct epimeral plates. Urosome scarcely more than 

 half the length of the anterior division, and rapidly tapering behind ; genital seg- 

 ment considerably dilated in front, and divided in the middle by a somewhat 

 curved transverse line; last caudal segment longer than the preceding one. Caudal 

 rami closely juxtaposed and somewhat applanated, being slightly longer than they 

 are broad at the base, outer edge armed with a short spine beyond the middle, 

 apical seta? scarcely diverging at. all, the innermost but one much the longest. 

 Anterior antennae unusually slender, with the joints of the proximal part con- 

 siderably prolonged, the 2nd joint being the largest, terminal part not nearly 

 attaining half the length of the proximal part. Posterior antenna? likewise rather 

 slender, with the terminal joint long and narrow, outer ramus not nearly half as 

 long as the latter, and provided with 4 seta3, 2 apical and 2 lateral. Posterior 

 maxillipeds with the hand very large and deeply concaved inside, dactylus strong 

 and curved. 1st pair of legs rather slender, rami very unequal, the outer one 

 scarcely more than half as long as the inner, last joint somewhat shorter than 

 the other 2, and provided with 3 spines successively increasing in length, and a 



