14 



MARINE ISOPODS FROM THE PHILIPPINE ISLANDS. 



This species is very close to Rocinela vigilans Haswell, a but differs in having a small 

 V-shaped space on the dorsal surface of the head in front of the eyes, and in having the 

 posterior extremity of the abdominal segment and the uropods denticulate, which are 

 described by Haswell as "smooth, entire." Rocinela vigilans may have been referred 

 to the wrong genus, but at present it is impossible to do otherwise than accept the 

 author's account and figures of this form. It is also close to Mga cy clops Haswell, 

 'which is not figured and is briefly described. & 



2Ega truncata, sp. nov. 



Body ovate, a little more than twice as long as wide, 15 mm.: 34 mm. Surface 

 smooth. Color yellow, marked with small brown dots. 



Head wider than long, 2.5 mm.: 7 mm., with the anterior margin produced in a 

 median triangular process very acute and long, the length of the head, including the 

 process, being 3.5 mm. The eyes are large, oval, composite, placed in an obliquely 

 transverse position and occupying most of the dorsal surface of the head, being 1.5 

 mm. apart. Each is 3 mm. in length and 1.5 mm. wide. The first pair of antennae 

 have the first two articles greatly dilated and flattened, the 

 first being as wide as long (1.5 mm.); the second article is as 

 wide as the first and has the anterior angle produced in a 

 large rounded process, the posterior angle in a very small 

 rounded process; the third article is short and very narrow 

 and does not extend beyond the anterior process of the second 

 article; the flagellum is composed of eleven articles and ex- 

 tends to the posterior margin of the head or to the end of the 

 peduncle of the second pair of antennae. The second pair of 

 antennae have the first and fourth articles of 

 the peduncle short and subequal ; the second 

 and third together are equal in length to the 

 first; the fifth is twice as long as the fourth; 

 all are rather dilated and flattened. The flagel- 

 lum is composed of sixteen articles and ex- 

 tends to the posterior margin of the first tho- 

 racic segment. The frontal lamina is broader 

 anteriorly than posteriorly; the sides are 

 straight and slightly converging; the anterior 

 margin is almost straight, but on close obser- 

 vation is seen to be produced in a small median point. 



The first segment of the thorax is the longest and is 4 mm. in length; the five follow- 

 ing segments are subequal and each is 3 mm. long; the seventh is the shortest, being 

 2.5 mm. long. The first segment has no epimera, but there is a distinct carina on the 

 lateral margin on either side. The following six segments are provided with wide 

 epimera, on each of which there is a double oblique carina. All the epimera are 

 rounded posteriorly and none are very much produced. 



The first segment of the abdomen is concealed in the middle of the dorsal surface 

 but is visible at the sides; the second and third segments are subequal in length and 

 each is 1 mm. long; the fourth segment is about 1.25 mm. in length; the fifth is 1.5 

 mm. long; the sixth or terminal segment is 9 mm. wide at the base and is 6.5 mm. 

 long. The sides curve slightly and converge to a truncate extremity, the postlateral 

 angles being rounded. The branches of the uropoda are subequal in length and reach 

 the extremity of the terminal abdominal segment; the outer branch is slightly nar- 

 rower than the inner branch and has the posterior extremity rounded; the inner 

 branch is posteriorly truncate. The margins of the uropods and the terminal abdom- 

 inal segment are smooth and furnished with hairs but no spines. 



Second leg. X 7%. 



Fig. 13.— Mga truncata. Xl 2 l . 



a Proc. Linn. Soc, New South Wales, vol. v, 1880, p. 472. 

 b Ibid., vol. vi, 1881, p. 192. 



