REl'ORT ON THE ISOrODA. 69 



12. Serolis australiensis, F. E. B. (PL VI. figs. 3-8). 



Serolis australiendx, F. E. Beddard, Proc. Zool. Soc. Lond., 1884, pt. iii. p. 334. 



Of this species three examples were obtained by the Challenger off the coast of South 

 Australia, and I have been able to compare them with a specimen in the British Museum 

 lirought from the same locality. 



The largest specimen is a female (PL VL fig. 4) and measures 14 mm. in length by 

 1 1 mm. in greatest breadth; the two remaining specimens are both males (PL VL figs. 3, 7), 

 and are approximately of the same size, measuring 10 "5 mm. in length and 9 mm. in 

 breadth. 



Apart from the form of the third thoracic and second abdominal appendages, I could 

 detect no marked differences between the two sexes, unless it be that the females are 

 really larger than the males in this and in the other Australian species. 



The general form of the body of Serolis australiensis is oval, the male a little broader 

 proportionately ; the distinguishing feature of this species is the immense number of 

 tubercles which cover the body, and are especially large upon the caudal shield and the 

 posterior margin of the segments. 



The cephalic shield is broadest at the level of the eyes, where it bulges out considerably 

 on either side. Anteriorly and posteriorly it is narrower ; the anterior margin is prolonged 

 into a very long rostrum ; there is a transverse ridge which forms the anterior margin of 

 the caudal shield for a short distance on either side of the rostrum, and then bifurcates, 

 the outer branch continuing along the anterior margin of the cephalic shield and giving 

 off a short spine directed forwards at the level of the end of the first joint of the anterior 

 antennse ; the inner branch follows the margin of the cephalic shield, but at some little 

 distance from it, and the two unite at the lateral anterior angle, enclosing between them 

 a somewhat boat-shaped depression. The tubercles on the cephalic shield are arranged 

 in transverse rows ; there is a larger spine just to the inside of the posterior third of the 

 eye on either side directed backwards and slightly outwards, and a median spine about 

 the same size situated near the posterior margin of the cephalic shield. 



TJiorax. — The epimera of the first segment are not divided by a suture. The three 

 following epimera are closely applied to each other along their whole length ; there is a 

 slight break between the four anterior and the two posterior epimera ; the two latter are 

 closely applied to each other, but the outer margin of the fifth begins to curve backwards 

 a little before the outer termination of the fourth epimeron, so that the angle of the latter 

 projects freely. All the thoracic epimera, with the exception of the first, are separated by 

 a suture from the tergal portion of the segments. 



The terga of the thoracic segments, as well as the epimera, are covered with minute 

 tubercles, which are distributed in longitudinal rows running from one side of the segment 

 to the other ; one row, which is constant in all the segments, and is rather more conspi- 



