64 



taining only a very limited number of ova. Seminal receptacle of quite a similar 

 shape to that in the other species of the present genus, the anterior part being 

 bilobular, the posterior greatly produced tongue-shaped. 



Colour, according to Lilljeborg, dark brownish, or light greyish brown. 



Length of adult female about 0.80 mm. 



Remarks. Through the kindness of Prof. Wiren of the Upsala University 

 I have had the opportunity of examining this interesting species, and have thereby 

 found my above-indicated suggestion about the systematic position of this form 

 fully confirmed. In spite of the reduction of the number of joints in the anterior 

 antennae and the imperfect development of the legs, it must, in reality, be 

 referred to the present genus, with which it otherwise agrees perfectly. Its 

 resemblance, indeed, both as regards size and general appearance, to one of the 

 above-described species, viz., M. oithonoides, is so perplexing, that at first sight it 

 might even easily be confounded with that form. It will be found that the above- 

 mentioned differences in the structure of the anterior antennae and the legs are 

 quite analogous to those observed in certain species of the genus Cyclops (sens, 

 strict.), and are merely due to a retarded development of these appendages. 



Occurrence. This form, it is true, has not yet been observed within the 

 limits of our country; but, as it occurs in the neighbouring parts of Sweden, it 

 is very probable that, on a closer investigation, it will in reality be found in some 

 place or other in the south-eastern part of the country. 



Distribution. Sweden (Lilljeborg), Germany (Schmeil), Poland (Lande). 



Gen. PaehyCyClOpS, GK 0. Sars, n. 



Generic Characters. Body robust, with the anterior division much dilated 

 and boldly vaulted above. Epimeral parts of the trunk- segments not produced 

 laterally; last segment very small. Tail not very slender, with the genital 

 segment of moderate size and only slightly dilated in front. Caudal rami com- 

 paratively short, but with the apical setae well developed. Anterior antennae long 

 and slender, 17-articulate. Posterior antennae likewise slender, with long curved 

 apical seta?. Maxillipeds comparatively shorter and stouter than in Mesocydojis. 

 Natatory legs normally developed, with both rami 3-articulate, terminal joint of 

 outer ramus in 1st to 3rd pairs with 3 spines outside, in 4th pair with only 2 

 such spines, inner edge of this joint carrying in 1st pair 3, in the succeeding 

 pairs 4 setae. Last pair of legs biarticulate, proximal joint more or less pro- 



