26 MR. E. J. MIERS ON CRUSTACEA FROM [Jan. 14, 



vex and well defined ; and there is a very prominent conical tubercle 

 upon the cardiac region which is not bilobate, also a broad lobe or 

 tubercle upon the hepatic region. The eye-peduncles are smooth ; 

 the posterior legs have the last joint but shghtly falcated. The postab- 

 domen of the male is broader than in the preceding species, the ter- 

 minal segment transverse. Length (of male) nearly j^ inch, breadth 

 nearly -J inch. 



Specimens were collected at a depth of 36 fms., in lat. 33° 10' N., 

 long. 129'' 12' E. J and there are others without definite locality at- 

 tached. 



This species resembles the Ackceus lacertosus of Stimpson (Proc. 

 Ac. Nat. Sci. Phil. p. 218, 1857), from Australia, Port Jackson, in 

 the distinctly defined regions of the carapace, the presence of an 

 hepatic lobe, and the smooth eye-peduncles, but differs in the very 

 prominent tubercle or blunt spine on the cardiac region, which is 

 present in both sexes, whereas Stimpson, in his description of Achcp.us 

 lacertosus, says, " super fide Ixevi spitiis carente." I must there- 

 fore regard it as distinct. Stimpsou's species was from Port Jackson, 

 Australia. 



Achceus japonicus, De Haan (Faun. Jap. Crust, p. 99, pi. xxix. fig. 

 3, 1839), is described and figured as devoid of spines on the carapace, 

 and the eye-peduncles as being 4-spinulose ; there is no hepatic lobe. 



Hyastenus diacanthus. 



Naxia diacantha, De Haan, Faun. Japon. Crust, p. 96, pi. xxxiv. 

 fig. 1, and pi. G (1839). 



Hyastenus diacanthus, A.M.-Edw. Nouv. Archiv. Mus. Hist. Nat. 

 viii. p. 250 (1872). 



Hyastenus verreauxii, A.M.-Edw. I. c. p. 250 (1872). 



A single male specimen of this common inhabitant of the Japanese 

 seas was obtained at Ousima, Japan, in 9 fathoms of water on a 

 sandy bottom. 



Two other specimens of this genus are in the collection ; the first, 

 a small female specimen, was collected in lat. 33° 4' N., long. 129° 

 18' E., at a depth of 23 fathoms. All the limbs are unfortunately 

 missing. It diffiers in the much greater divergence of the horns of 

 the rostrum, and very probably belongs to a distinct species ; but, on 

 account of its mutilated state, I refrain from describing it as such. 



In the second, the horns of the rostrum are more than half the 

 length of the carapace and but slightly divergent ; the carapace is 

 convex, narrower and more elongated than in Hyastenus diacanthus, 

 and without any spines or tubercles, and is covered with a very short 

 close pubescence. 



This specimen is also an immature female, and was obtained at a 

 depth of 18 fathoms, near Cape Sima. It would not be advisable 

 to make this the type of a new species by giving it a distinct appella- 

 tion ; but it is distinguished from its nearest ally, H. diacanthus, by 

 the total absence of the lateral epibranchial spines, which are present, 

 although very small, in examples of H. diacanthus of the same size. 



