17 



Nautilocorystes octodentatus (de Haan). 



1833. Corystes [Dtcera] Z-dentata, de Haan, Fauna Japonica, 



Crust., Decas i, p. 15. 

 1837. Nautilocorystes ocellatus, Milne-Edwards, Hist. Nat. 



Crust., V. 2, p. 149, 

 1843. Dicer a S-dentata, Krauss^ Siidafrik. Crust., p. 27. 

 1857. Nautilocorystes ocellatus^ Stimpson, Proc. Ac. Nat. 



Sci. Philad., Prodromus, p. 23. 



The specific name chosen by de Haan evidently refers to 

 the prominent teeth of the antero-lateral margins, the teeth 

 of both sides being added together to form the number eight, 

 a method which is followed also in naming the species 

 Oeidia 20-spinosa. In the present instance there is a slight 

 complication, because in the generic account de Haan speaks 

 of the thorax as being " 5-spinosus " on the sides. He is 

 then evidently including the small tooth at the outer corner 

 of the orbit, which in the specific name he leaves out of 

 reckoning as an inconspicuous feature. The name given by 

 Milne-Edwards no doubt refers to markings on the carapace, 

 which in the specimen here described are very suggestive of 

 the name ocellatus. In spirit they appear as thin reddish 

 brown lines forming irregular ovals or circles, of which the 

 four principal ones are disposed in a broad quadrilateral. The 

 upper pair rather detract from the mask-like appearance of 

 the carapace, being wider apart and rather too high up to 

 suit for eyes or spectacles to the mask. 



The carapace is 32 mm. long by 26 mm. in greatest 

 breadth, the front with a rather deep notch in the centre, 

 thence sloping with a faint emargination to the orbits, in 

 which the upper margin has two little unequal notches, the 

 smaller near the outer tooth, while below the pterygostomian 

 region is produced into an escutcheon-like piece, not spinose 

 as in Corystes, its apex reaching rather beyond the front of 

 the carapace, giving the appearance of a prolonged orbit, 

 though only the base belongs to the little narrowly-ending 

 eyes, and the mouth is blocked by the hairy basal joints of 

 the second antennae. Of the teeth on the antero-lateral 

 margin the fifth is about as large as the second, both are 

 smaller than the third and fourth, and all four are acute. 

 The upper part of the branchiostegite, the proximal parts of 

 the legs, and a line across the sternum between the second 

 and third pairs of legs are densely hairy. The second 

 antennae are 24 mm. long, or possibly rather longer. The 

 chelipeds are 37 mm. long. The female being apparently as 

 yet unknown, it cannot be said whether these limbs show any 

 sexual distinction parallel to that in Corystes. The fourth 



