79 



structure. Anterior antennae of moderate length, not dilated in the middle. 9- 

 articulate. Posterior antennae with the apical setae comparatively short, outer 

 ramus fully as long as the inner and 3-articulate, with one of the apical setae 

 much elongated. Mandibtilar palp rather large and complex, produced in front 

 to a digitiform, finely ciliated process. Maxillae with the epipodal plate very 

 large and tipped with 2 exceedingly strong plumose setae. Maxillipeds com- 

 paratively small and simple in structure, the anterior ones without any lateral 

 lobes, terminal joint small and tipped with 2 ciliated spines; the posterior ones 

 with a single comparatively short claw at the tip. First pair of legs rather large 

 and of a very delicate structure, with both rami flattened and somewhat resembling 

 those in the genus PorcelUdium ; inner ramus, however, distinctly 3-articulate, 

 with the 1st joint large and dilated in the middle, the outer 2 comparatively 

 short, last joint carrying 2 digitiform claws densely fimbriate on one side. Na- 

 tatory legs with both rami of nearly equal length, middle joint of inner ramus 

 in 1st pair with 2 setse inside, in the 2 succeeding pairs with only one. Last 

 pair of legs differing somewhat in shape in the two sexes, those in female rather 

 coarse, with the proximal joint elongated and scarcely at all expanded, distal 

 joint more or less lamelliform. 



Remarks. This genus was established by Norman in the year 1868, to 

 include a form found by him off the Shetland Isles and named A. fasciatus. The 

 genus was not, however, accepted by Prof. Brady, who in his Monograph referred 

 Norman's species to the genus Scutellidium Glaus (= Psamathe Philippi), to which 

 genus it certainly exhibits a close relationship. I think, however, that Norman's 

 genus ought to be maintained, since 2 nearly-related species exist showing the very 

 same characteristic differences from Claus's genus, which likewise comprises 2 or 3 

 closely-related species. The most characteristic feature of the present genus 

 consists in the peculiar fornicate condition of the 3rd free segment of the meta- 

 some, a character not found in any other Copepoda with which I am acquainted. 

 Moreover, on a closer comparison, several well-marked differences are found to 

 exist in the structure of some of the appendages. The genus comprises, as above 

 stated. 2 well defined species, to be described below. 



48. Aspidiscus littoralis, G-. 0. Sars, n. sp. 



(PI. XLVI & XLVII). 

 Syn: Scutellidium fasciatum, Brady (not Norman). 



Specific Characters. Female. Anterior division of body very broad, 

 scarcely narrowed behind. Cephalic segment large, occupying more than half 



