19 



The styliform terminal segment of the antenna is another small character in which the present 

 form approaches the Lampropidce ^ especially the genus Paralamprops. In that family, on the 

 ether hand, the flagella of the antennule do not as a rule differ greatly in length. On these 

 grounds, and notwithstanding the incompleteness of the account which I am able to give of 

 this new species, I have found it necessary to estabhsh for it a new genus, placing it for 

 the present among the Diastylidae on the ground of its similarity to them in general form. 

 From all the described genera of the family it is separated by having three terminal spines 

 on the telson. Should it prove necessary, in the future, to transfer it to the Lampropidtr , 

 the genus will still be sufficiënt!) distinguished by its inflated carapace and large pseudo- 

 rostrum. Other characters which may prove to be of generic value are the great size of 

 the outer ramus of the antennule, and the pediform third maxillipeds, while the remarkable 

 spinous armature of the carapace distinguishes the species at once from all Cumacea hitherto 

 described. 



Diastylis. 

 I. Diastylis cingulatus n. sp. Plate II, figs. 26 — 29. 



Description of young Male. Total length 15 mm. 



The carapace is sub-globose, % of the total length, its transverse width a little more than 

 three-quarters, and its vertical height about two-thirds, of its length. It is encircled by a stout 

 ridge which crosses the dorsal surface a little behind the middle and inclines a little forward on 

 each side. The pseudorostrum is long, horizontal and rather sharply pointed, the pseudorostral 

 plates m.eeting for about one fiftli of the length of the carapace. There is no eye and no ocular 

 lobe. The strongly curved lower margin of the carapace runs obliquely upwards into the lower 

 edge of the rostrum without any distinct antero-lateral angle or antennal notch. The whole 

 surface of the carapace is beset with spines which, in the specimen figured, are nearly all broken 

 off close to the base. The encircling ridge bears the stumps of a series of stout spines closely 

 set throughout its whole length. In front of the ridge the spines are smaller and more closely 

 set than behind it and most of those which remain unbroken are hook-shaped, with the distal 

 part roughened with small tubercles (PI. II, fig. 28). On each side of the anterior part of the 

 carapace is set a single stout, straight and smooth spine a little longer than the uncinate spines 

 surrounding it. Behind the ridge, the spines are short, stout and conical. On the upper surface 

 of the pseudorostrum, close to the tip, are the bases of a pair of rather stout spines. The lower 

 margin of the carapace bears throughout its length a close-.set series of spines which posteriorly 

 are short and very thick but anteriorly become long and slender. 



The first leg-bearing somite is exposed dorsally but is covered at the sides by the second. 

 The third and fourth are fused together, and their pleural plates are not expanded. The lateral 

 processes of the last thoracic somite are not produced, and the articulation of the legs is 

 displaced towards the dorsal surface. 



The abdomen is rather slender and, including the telson, about one-third longer than 

 the cephalothoracic region. All the somites as well as those of the thorax, are beset with small 



