30 



(x. O. SAES. 



[No. 8. 



figure reproduced by Mr. Schoedeler, from the present form, 

 alike as regards its general habitus and the number of natatory 

 setæ on the antennæ. The M. micrura of Kurz, from South 

 Germany, has the antennulæ, as in the present species, densely 

 ciliate posteriorly, but differs, let alone other characters, in the 

 terminal part of the tail being far less produced and armed with 

 a much smaller number of lateral denticles. 



Description of the Female. — The largest specimen 

 examined had a length of 1,14 mm, or nearly that of the Northern 

 species. The general form of the body (see Pl. 5, figs. 4, 5) is 

 much the same as in M. brachiata, being, more especially in 

 gravid specimens, rather short and clumsy. 



The head is marked off from the carapace by a distinct 

 dorsal impression, from which proceeds a well-defined transversal 

 su ture, joining the upper ends of the mandibles. In a lateral 

 aspect (fig. 4), it appears somewhat depressed, with the dorsal 

 contour strongly arched behind, whereas anteriorly it becomes a 

 trifle concave, forming an indistinct sinus above the eye. The 

 front projects a little, but still less than in M. brachiata, and is 

 narrowly rounded, with the ventral margin well-nigh straight. 

 No true rostrum is present, the posterior part of the head forming 

 beneath but a slight convexity previous to its joining the labrum. 

 As seen from above (fig. 5), the head tapers very slightly toward 

 the apex, which is obtusely rounded. A slight trace only of the 

 fornix is seen projecting on either side just above the bases of 

 the antennæ. \ 



The carapace is much broader than the head, and, in gravid 

 specimens, expanded on the dorsal side in a truly remarkable 

 manner, to form a most capacious, well-nigh globular matrix 

 (see figs. 4, 5), marked off, it would appear, from the valves inferi- 

 orly by a curved chitinous fillet, projecting from its inner face 

 (see fig. 3). Posteriorly, the carapace juts out as a short and 

 obtuse prolation, below which the free parts, or valves, take 

 their origin. The latter are comparatively small, so as not to 

 obtect fully either the oral parts or the tail. Anteriorly, they 

 exhibit in their upper part a well-marked sinus, leaving uncovered 



