546 



is shorter and narrower than the endopodite. The telson is fused with the 

 last urosomite and together they form a regular triangle; the margins of 

 the telson are straight and the tip is rounded. 

 Type species: Typhis ovoides Risso, 1816. 



KEY TO SPECIES OF GENUS PLATYSCELUS 



1. Coxal plates V form spiniform lateral processes, variably developed 

 but always noticeable 1. P. armatus (Claus). 



— Coxal plates V do not form spiniform process 2. 



2. Abdomen tucked under pereon* and pereopods under body so that 

 crus-tacean acquires on oval shape. In pereopods I and II, 6th seg- 

 ment denticulate at least in distal half of anterior margin 1 



P. ovoides (Risso). 



— Generally abdomen and pereopods not tucked under body and crus- 

 tacean not oval in shape. Sixth segment of pereopods I and II smooth 

 along anterior margin 3. 



3. Distal process of 5th segment of pereopods I not reaching middle 

 of 6th segment. Second segment of pereopods V with undulating 

 anterior margin. Second segment of pereopods VI with one notch 



each in distal and proximal parts of anterior margin 



4. P. crustulatus (Claus). 



— Distal process of 5th segment of pereopods I reaches 2/3 length of 

 6th segment. Second segment of pereopods V and VI with smooth 

 anterior margin 3. P. serratulus Stebbing. 



1. Platyscelus ovoides (Risso, 1816) (Fig. 235) 



Risso, 1816: 122 (Typhis); Claus, 1879b: 9 (Eutyphis); 1887: 

 35 (Eutyphis); Stebbing, 1888: 1463; Chevreux and Page, 1925: 

 420; Stephensen, 1925a: 213.— ferus Milne-Edwards, 1830: 395 

 (Typhis). — intermedins Thomson, 1879: 244. — globosus Claus, 1879b: 

 13; 1887: 38 (Eutyphis). 



Length of sexually mature specimens up to 20 mm. 



The body is very compact, the integument thick, the abdomen tucked 

 under the belly and the pereopods under belly the body so that the crus- 

 tacean acquires an egg shape (whence the name of the species). The 2nd 

 segment of pereopods V and VI forms a compact strong shell on the 

 ventral side, under which the female rears eggs and young . The head 

 in height is twice its length and thrice its width. The pleon is high and 

 broad, its width more than its length. Somites I and II of the pereon 

 together are equal in length to somite III. 



[sic]; here and subsequently — General Editor. 



