REPORT ON THE CRUSTACEA MACRT7RA. 19 



Thalassimi scorpionoides, Latreillc (Pis. III., IV.). 



Thalassina scorpionoides, Latr., Gen. Ins. et Crust., torn. i. 



Cancer anomalus, Herbs t., torn iii. tab. 62. 



Thalassina scorpionides, Leach, ZooL Misc., vol. iii. p. 28, tab. 130; Desmarest, Consider, des 



Crustacea, p. 203, pi. xxxv. figs. 1,2 a, b, r ; Milne-Edwards, Hist, des Crust., torn ii. p. 



316; Atlas du Regne anim. de Cuvier, Crustaces, pi. xlviii. fig. 1 ; Heller, Russ. frigate 



"Novara," p. 93. 



Habitat. — Kandavu, Fiji Islands. One specimen. 



Length, 225 mm. (9 inches). 



The eyes are small, movable, and subcorneal in shape. Deposited in an imperfect 

 orbit, formed by the obliquely directed inferior surface of the rostrum, on the. inner 

 side ; by two teeth, one on the upper and outer angle being the anterior extremity of a 

 short, smooth ridge or crest ; the second, a smaller tooth, immediately beneath it ; and 

 on the lower side by an excavation in the upper surface of the inner antenna?, where a 

 fringe of posteriorly directed hairs, coterminous with others that are anteriorly directed 

 from the side of the rostrum, as well as. from the upper external circuit of the orbit, forms 

 a blepharis that surrounds and protects the eye. 



The first pair of antennae has the inner surface of the first joint compressed and 

 flattened against that of the opposite side, the other surfaces slightly converging, and 

 directed upwards; the second joint is much smaller and also directed upwards, the upper 

 surface being slightly concave, and, with that of the first joint, forms a hollowed floor on 

 which the eye rests ; the upper surface of the first or coxal joint is perforated by an 

 elongated triangular foramen or slit, the entrance to the auditory chamber, which is 

 protected by a dense mass of ciliated hairs, also continuous within the auditory passage. 



The auditory apparatus consists of a large calcareo-membranous chamber, attached to 

 the upper wall of the antenna. Around the orifice that opens into it, within the chamber, 

 there is a curved row of closely-planted delicately-ciliated hairs, each of which is 

 attached to the base by a flexible membranous articulation, from which it proceeds 

 flattened and tolerably broad for more than half its length, when it narrows rapidly 

 and becomes cdiated, the cilia being short and fine ; the hairs extend nearly if not 

 quite across the auditory chamber, the floor of which is covered with small points, 

 while the cavity contains much angular calcareous sand. This I found mostly gathered 

 into a compact mass, but most probably when the animal was in a living condition it was 

 not so, being then kept in a state of motion by the aid of the long slender ciliated hairs 

 that have just been described. The auditory chamber occupies about two-thirds of the 

 cavity of the first joint of the antenna. 



The second pair of antennae is in the same horizontal line with the first, immediately 

 outside, being separated by a very narrow septum or calcified ridge. The five joints of 

 which the peduncle is formed are separately defined, and this enables us to demonstrate 



