Species of Maioid Crustacea. 15 



and sometimes the succeeding pairs) armed with a strong spine. 

 Postabdominal segments smooth, distinct. Length of carapace 

 in the largest individual ■§ inch. 



Hah. Fiji Islands, Ngau, Totoya, Ovalau; Conway Reef 

 {H.M.S. 'Herald'). 



The tubercles of the carapace are larger posteriorly, and 

 are most distinct in the oldest individuals. In some examples 

 the carapace is narrower and the rostral spines are longer ; 

 but these are not characters confined to one or the other 

 sex. This species inhabits the coral reefs. 



To facilitate the identification of the types of this new 

 genus, I have given at length the description of the above, 

 which I refer with some hesitation to the Cancer styx of 

 Herbst. It is certainly the species figured by M. A. Milne- 

 Edwards (I. c.) as Microphrys styx. 



There is an adult male from the Mauritius in the British- 

 Museum collection, which differs from an adult male of the 

 species described above only in the greater enlargement of the 

 hands, and in the greatly arcuated fingers, which meet only 

 at the tips. I am not disposed to regard it as distinct, since 

 M. A. Milne-Edwards has noted that P. styx is distributed 

 throughout the Indo-Pacific region. 



Tylocarcinus gracilis, sp. n. 



Carapace elongate-pyriform, surface covered with granules 

 and small tubercles. On the front of the gastric region are 

 several small granules followed by four in a transverse line ; 

 the branchial, cardiac, and intestinal regions are very indis- 

 tinctly tuberculated. The spines of the rostrum are long, very 

 slender, and divergent nearly from their base. The spines 

 on the third and fourth joints of the first pair of ambulatory 

 legs are long and acute. 



Hob. " Eastern seas " {H.M.S. ' Herald'). 



This species differs from the foregoing principally in the 

 much narrower and less distinctly tuberculated carapace, and 

 in the form of the rostrum, and may perhaps prove to be only 

 a variety of it ; the spines of the rostrum are in T. gracilis 

 more than half the length of the carapace ; in T. styx they are 

 much less than half its length. 



Othonia quadridentata, sp. n. (PI. V. fig. 1.) 



Carapace rather broadly ovate, and smooth, without any 

 trace of tubercles or granules. Lateral margins armed with 

 four well-developed acute spines, without any trace of the fifth 

 and sixth spines, which are observable in other species of this 



