23 



10. Cymbasoma Thompsoni, (Giesbrecht). 



(PI. XII) 



Thaiimaleiis Thompsoni, Giesbrecht, Pelagische Copepoden des Golfes von Neapel, p. 584, 



PI. 46, figs. 7, 27, 31, 36, 40. 



Syn. Monstrilla Dana, Moebius (non Claparede) 



Specific Characters. Female. Body comparatively more slender than in 

 the preceding species, with the cephalic segment narrower and considerably 

 exceeding in length the remaining part. Tail very short, scarcely longer than 

 the last 2 trunkal segments combined; genital segment unusually tumid, seen 

 dorsally almost circular in outline, ventral face strongly protuberant, ovigerous 

 spines of moderate length; distal segment without any traces of lateral notches. 

 Caudal rami rather small, each provided with 3 subequal setae; no appedicular 

 bristle present. Eye apparently well developed. Antennae scarcely attaining 

 YS of the length of the cephalic segment, and of a structure very similar to 

 that in the preceding species. Oral tubule somewhat more approximate to the 

 frontal part of the head. Natatory legs with the outer ramus considerably 

 longer than the inner, and the terminal joint more produced than in the 

 preceding species. Last pair of legs resembling in structure those in C. rigidum, 

 though having the innermost of the apical setse rather smaller and the lobe 

 of the inner edge less prominent. 



Male comparatively more slender than that of the preceding species, 

 and having the cephalic segment shorter and less pronouncedly clavate in 

 shape. Tail composed of 3 well defined segments, the last of which, as in 

 female, does not exhibit any traces of lateral notches. Caudal rami of the 

 very same structure as in the female, each ramus being only provided with 3 

 setae. Antennae very strongly built, with the joints rather expanded, the 

 last one very mobile and somewhat thickened at the extremity, which is 

 armed with 2 small denticles. No traces of a 5th pair of legs present. 

 Copulative appendage comparatively smaller than in the preceding species, 

 with the terminal lobes less produced. 



Colou: of the living animal not yet assertained. 



Length of adult female 1.20 mm., of male 0.80 mm. 



Remarks. The precent species was described by Giesbrecht from some 

 specimens taken in the Baltic, east of Langeland, and sent to him from 

 Moebius, who had previously recorded this form under the name of Monstrilla 

 Dance, Claparede. It may easily be distinguished from the preceding species 

 by its much inferior size, and more particularly by the rather different shape 



