34 



reaching, when reflexed, considerably beyond the 2nd segment, and having some 

 of the marginal setse rather slender. Posterior antennse with the terminal joint 

 longer than the penultimate one and much narrower. Anterior maxillipeds with 

 the claw of the 2nd basal joint comparatively longer than in C. strenuus. Nata- 

 tory legs having the same number of spines and setse as in that species, rami, 

 however, considerably more slender, especially those of 4th pair; apical spines 

 of inner ramus in this pair more elongated, the outer one about half as long as 

 the inner. Last pair of legs with the proximal joint comparatively less broad 

 than in C. strenuus, distal joint about twice as long, and having the lateral spine 

 of moderate size and attached nearly in the middle of the inner edge. Ovisacs 

 smaller than in the preceding species and rounded oval in form, each containing 

 a rather limited number of ova. Seminal receptacle comparatively small, with 

 the anterior part evenly rounded. 



Colour whitish grey, with a slight yellow tinge more distinct on the tail. 



Length of adult female 1.80 1.90 mm. 



Remarks. The above-described form is closely allied to C. strenuus, and 

 has indeed by most recent authors been regarded as only a variety of that species. 

 We know, however, at present of several species exhibiting a similar close relation- 

 ship to C. strenuus, and together forming a natural group of Cyclopses. All of 

 these have, it is true, been combined by Dr. Schmeil in a single species; but in 

 recent time, the specific distinctness of some of these forms has been fully recog- 

 nized. Thus Lilljeborg, in his account of the Swedish Cyclopses (1901), de- 

 scribes as well-defined species the 2 forms C. scutifer, G-. 0. Sars and C. vicinus, 

 Uljanin, which are both recorded by Dr. Schmeil as only synonyms of C. strenuus. 

 Though Lilljeborg was inclined to regard the present form as merely a "luxuri- 

 ant" deep-water variety of C. strenuus, it is in my opinion fully as distinct from 

 that form as are the 2 just-named species. On a closer comparison, it is in reality 

 found to differ conspicuously from C. strenuus, both as to its outward appear- 

 ance and the structure of some of the appendages. Among more easily observable 

 differences I may mention the greater length of the anterior antennae, the very 

 narrow form of the caudal rami, and the somewhat different mutual relation in the 

 length of the apical setse. It may moreover be noted here, that the form of the 

 seminal receptacle, on which Dr. Schmeil laid so much stress for the discrimination 

 of species, is in the present species rather different from that in C. strenuus, as 

 shown by the figures given in the 2 respective plates. The form recorded by 

 me from the lake Telecki in Altai as C. strenuus, var. gracilipes, I now find to 

 be more properly referable to the species here under consideration. 



