'212 COPKPODA. 



PHYLLOTHYREUS CORNUTUS (H. Milne-Edwards). (PI. XXIV. 

 figs. 9-17.) 



1840. Plnjllopliora cornuta, H. Milne-Edwards, Hist. Nat. Crust. 



p. 471, pi. xxxviii. fig-. 13, 14. 

 1903. Phyllothyreiis eornutus, Norman, Ann. & Mag. Nat. Hist. 



ser. 7, Vol. xi. p. 368 (April, 1903). 



More than forty years ago Win. Laughrin, who was en- 

 gaged in collecting fish parasites at Polperro, Cornwall, for 

 A. M. N., sent him two specimens of this most interesting 

 species. They were found on the Blue Shark (Carchavias 

 (flaucus). The only other previously known habitat of the 

 species was, according to Milne-Edwards, Tongatabu in the 

 Friendly Islands, whence the type specimens came ; this is, 

 therefore, a remarkable instance of wide distribution. The 

 name Plnjllopliora having been previously employed, Pliyllo- 

 thi/reus (1. c.) has recently been substituted for it. 



The cephalosome is devoid of any metasornatic region, 

 since all the feet are attached to separate segments; it is 

 semioval in form, deeply emarginate behind, and the lateral 

 arese widely rounded distally. No separated frontal plates. 

 Three segments of the metasome bear dorsally large leaf-like 

 processes, which laterally extend far beyond the margins of 

 the cephalosome. The urosome is composed of two segments; 

 the first of these (i. e. the genital) is nearly round, and bears 

 at the corners of the truncated hinder margin ovate processes 

 which represent the fifth feet ; the last segment consists of 

 two transversely obovate leaf-like plates from between which 

 the very long egg-sacs are protruded. 



The antennnles (fig. 10) are small ; the second segment, 

 which bears the single spine, which is characteristic of the 

 hinder margin in the Caligoida, is much shorter than 

 the first joint. The antennules (fig. 11) are enormously 

 developed, and protrude forwards far in advance of the 

 cephalosome, forming very powerful grasping organs. The 

 first maxillipeds (fig. 12) have the nails short and strong, 

 with a little spine-like process by the origin of the larger 

 one. The second maxillipeds (fig. 13) are very short, but at 

 the same time strong ; the palm is directly transverse, and 

 the short nail is strong. The first four pairs of feet are 

 biramose, the rami all leaf-like, so that the animal viewed 

 from below has the peculiar appearance which is well repre- 

 sented in Milne-Edwards's pi. xxxviii. fig. 14; the first pair 

 have the inner ramus two-jointed and the outer a single joint; 

 the second pair have both rami two-jointed; while in the third 

 and fourth pair the rami consist of only a single joint ; these 

 feet are entirely devoid of seise, bearing only a few small 

 spines, with the margin also in places very minutely ciliated. 

 Length 13 millim. 



