OS BOSNINIVM, MACJROTHRICID.E, ETC. 397 



1863. Pleuroxus transversus, Schoedler. Neue Beitrage zur 

 Naturg. der Cladoceren, p. 50. 



Carapace ovate, posteriorly subtruncate, ventral margin slightly 

 waved, fringed on the posterior half with a few cilia; dorsal 

 margin well rounded from the rostrum to the infero-posteal angle, 

 which is furnished with a single minute tooth ; surface curiously 

 sculptured with strongly marked oblique waved striae, which 

 instead of, as is the case in all other species, having their direc- 

 tion towards the infero-posteal angle, incline towards the supero- 

 posteal angle, or in other words, proceed from the front portion 

 of the ventral margin to the hinder portion of the dorsal margin ; 

 the carapace is unusually opaque, and of a dark colour. Head 

 depressed with a produced rostrum, which is bent downwards. 

 Eye-spot more than half the size of the eye, nearer to it than to 

 the extremity of the rostrum. Abdomen short, very deep, distal 

 angle rounded off, a very strongly developed anterior process ; 

 marginal teeth few (from seven to nine), extending to the base 

 of the claws ; claws small, with a very small spine springing 

 from the base. Length, Tiijth of an inch, the smallest of our 

 Cladocera. 



Sars thus describes the male of this species — "Mas femina 

 angustior rostro obtusiore antennisque primi paris majoribus in- 

 signis ; margo postabclominis posterior fere aequalis nullum pro- 

 cessum formans ; pedum primum par ut in ceteris Lynceidis 

 ungue curvato prseditimi." 



The sculpture of the valves of this species is very peculiar, 

 looking at the anterior margin it seems almost as though the 

 shell was composed of a number of superimposed plates ; the 

 striae ascend from the lower portion of the ventral margin directly 

 upwards, then suddenly bending backwards (the lower ones at a 

 very acute angle) they descend, with a more and more arcuate 

 sweep as they approach nearer to the head, to the hinder extre- 

 mity of the carapace. Moreover the striation is not, as in other 

 Lyncei, a mere superficial marking of the carapace, but consists 

 of a series of deep concave grooves, so that when the animal is 

 turned in the field of the microscope, so as to give a direct anterior 



