Prof. Allman on a new genus and species of Entomostraca. 3 



antennae followed by a pair of appendages (fig. 3) composed of 

 four joints, the terminal joint presenting itself under the form 

 of a hooked prehensile claw, and the basal bearing at its distal 

 extremity a double plumose seta. 



Situated at a short interval behind the last-mentioned pair of 

 appendages and occupying a position near the centre of the un- 

 der surface of the cephalic segment is the mouth, covered by a 

 largely developed upper lip (fig. 4), and guarded on each side by 

 a strong toothed mandible (fig. 5). External to the mandibles 

 are the first and second pairs of maxillae. Those of the first 

 pair (fig. 6) consist each of a flattened peduncle bearing two jointed 

 rami which are furnished with numerous plumose setae ; upon the 

 external ramus, one of these setae is very large, assuming the ap- 

 pearance of a flagelliform appendage, and a similar, though smaller 

 one, springs from the internal edge of the peduncle. The second 

 pair of maxillae (fig. 7) does not differ essentially from the first, 

 but is smaller and not furnished with such greatly developed 

 flagelliform setae. 



The maxillae are succeeded by two pairs of prehensile appen- 

 dages (figs. 8 and 9) : each consists of a large basal joint with a 

 terminal articulate stem ; stiff setae are carried upon the internal 

 side of both peduncle and stem, and on the stem one or more of 

 these becomes developed into a prehensile spine. 



Behind the last-described appendages, the cephalic segment 

 bears a pair of natatory feet resembling those which are borne 

 upon the succeeding segments of the body. 



There are altogether four pairs of natatory feet. The first of 

 these, as just mentioned, is borne on the cephalic segment ; the 

 second and third are supported respectively on the two distinct 

 rings which immediately follow ; while the fourth is placed below 

 the anterior end of the ovigerous region. Each of these natatory 

 feet (fig. 10) consists of a basal lamina composed of two joints, 

 and bearing on its distal edge two rami formed each of three flat- 

 tened articulations which are copiously furnished upon their inner 

 edge with plumose setae ; the setae borne by the external edge are 

 shorter and not plumose. The proximate joint of the basal lamina 

 carries upon its inner edge a plumose spine, and it is connected 

 with its fellow of the opposite side by an intermediate plate which 

 renders it necessary that the motions of the basal joints of each 

 pair of feet should be strictly in concert. 



The abdomen is somewhat cylindrical, and composed of about 

 five rings, the most posterior of which is prolonged, as in Cyclops, 

 by two diverging cylindrical appendages, each of which carries 

 upon its distal extremity four plumose setae. 



The external receptacle for the ova consists of a large dorsal 

 sessile sac, situated between the last distinct thoracic ring and 



1* 



