PHYLLOTHREUS CORNUTUS. 93 



towards the front which is truncated and without 

 frontal plates ; posterior edge deeply emarginate, and 

 with the lateral corners rounded. Thorax provided 

 with three pairs of leaf-like and suborbicular over- 

 lapping plates, which extend on each side to consider- 

 ably beyond the margin of the carapace and reach 

 backwards to a distance equal to the length of it. 

 Abdominal region distinctly narrower than the cara- 

 pace and composed of two segments; the genital 

 segment suborbicular, its length being rather less than 

 the width, and bearing, at the corners of the truncated 

 hinder margin, ovate processes which represent the 

 fifth pair of feet ; the last segment consisting of two 

 small transversely-obovate plates from between which 

 issue the two slender and elongated egg-strings. 



Antennules small, two-jointed, end joint narrow, 

 much shorter than the proximal one, and bearing a 

 few apical setae and a minute spine near the middle of 

 the lower margin; the antennae are represented by 

 large hooks which project considerably in front of the 

 carapace and form powerful grasping organs. First 

 maxillipeds with the end joint narrow and provided 

 with three terminal spines, the middle one being the 

 largest, tips of all three slightly hooked ; second 

 maxillipeds cheliform. Thoracic legs short, biramous, 

 and more or less lamelliform ; first pair with outer 

 ramus one-jointed and slightly geniculated, and the 

 inner two-jointed ; second pair with both rami two- 

 jointed ; while in the third and fourth pairs both 

 rami are uniarticulate. All the rami are devoid of 

 setae and bear only a few small spines. Length about 

 13 mm. Male unknown. 



Habitat. Parasitic on the blue shark, Garcha/rius 

 glaucus. Two specimens were collected by William 

 Laughrin at Polperro, Cornwall, many years ago, and 

 were sent by him to the Rev. Canon A. M. Norman. 

 " The only other previously known habitat of the 

 species was, according to Milne Edwards, Tongatabu 

 in the Friendly Islands, whence the type specimens 



