^GA BICARINATA. 279 



the larger size of the inner division of the appendages 

 at the sides of that part of the body, which is, moreover, 

 somewhat truncated at its inner extremity, whilst its 

 outer margin has a slight emargination near its extremity. 

 The eyes are wide apart and occupy the posterior angles 

 of the head. 



The upper antennae are scarcely longer than half the 

 width of the head ; the basal joint is large, flat, and 

 square, the second joint produced along its anterior mar- 

 gin so as partially to conceal the base of the third joint 

 (when seen from beneath), which is slender and succeeded 

 by a very short flagellum, consisting of five or six arti- 

 culi ; the lower antennae are about as long as the width of 

 the head, and have three short thick basal joints ; the 

 fourth is longer than the third, and the fifth nearly as 

 long as the fourth, but more slender, and is followed by 

 a flagellum, consisting of twelve articuli ; these organs 

 are separated at the base by a scutellum-shaped labrum, 

 arising from a transverse keel or epistome. At the sides 

 of each segment of the pereion the coxae of the legs are 

 developed as parts of the dorsal surface (epimera), and 

 have their outer portion raised and curved so as to form 

 elevated spines overlapping each other; the segments 

 themselves are marked across the middle, or nearer the 

 base, with a raised line ; the four anterior segments of the 

 pereion are of equal size. The surface of the pereion 

 is seen, under a strong magnifying power, to be entirely 

 covered with very minute circular punctures, amongst 

 which larger and more irregularly shaped ones are dis- 

 posed without order. 



Our drawing is made from Dr. Leach's original type 

 specimen in the British Museum, to which his own ma- 

 nuscript name is still attached. In this specimen the 

 extremity of the tail is formed precisely as represented 



