Mr H. Goodsii- on the Genus Ctima. 127 



tlie first joint is of no great breadtli. The natatory division is about 

 the same length as the first joint of the anterior division.* 



The second pair of legs arc very long and slender; the first segment is 

 not broader than the following joints^ and is armed internally at its ex- 

 tremity with a very long spine. t 



The simple feet are extremely spiny.|. 



The abdominal portion of the body is very long and slender, the fifth 

 segment being the longest. The caudal styles arc long, slender, and 

 pointed; the internal scale has the last joint pointed and armed with 

 two spines; the last segment of the external scale is more obtuse. || 



Genus Alauna, mihi.^ 



Generic Characters. — The superior antennae are composed of a peduncle 

 and a multi-articulate filament. The inferior antenncc are eight-jointed. 

 The three first pair of legs are compound. The internal scale of the 

 caudal style is composed of three segments, and the external of one. 

 Alauna rostrata, mihi. 



Description. — The whole animal is of a beautiful bright straw colour, 

 inclining to yellow. The thoracic j^ortion of the body is very large 

 and swollen. The first segment or carapace is almost oval. The ros- 

 trum is long, pointed, and is bent upwards at its extremity. The eyes, 

 which are of considerable slze^ are situated at the base of the rostrum. 

 The superior pair of antennse are very slender, consisting of a delicate 

 filament covered with hairs, which arises from a short peduncle ; these 

 antennse are almost equal in length to the rostrum." 



The inferior antennse are much longer, consisting of eight joints slightly 

 spinous ; the distal extremity of the third is armed with a strong multi- 

 articulate spine.' The foot-jaws are seen projecting considerably beyond 

 the edge of the carapace ; they are very spiny, and the- last joint but 

 one is armed with a long articulated spiniferous spine.'* 



The first pair of legs are extremely short ; the thumb-like process at the 

 extremity of the ambulatory division is single-jointed and spiniferous.^ 

 The second pair of legs are also short." The ambulatory division of 

 the third pair of legs is very long and slender, being almost as long as 

 that of the second pair of legs ; the fifth joint is the longest. The na- 

 tatory division is as long as the first four joints of the ambulatory.' The 

 simple legs are very spiny on tlieir anterior edges.' 



The abdomen is short and thick, seven-jointed, the last joint being pro- 

 duced into a long spine which is spiniferous on either edge ; the anal 

 .iperturc is seen near the base of this segment. The caudal styles arise 

 from the sixth segment, and they arc much more complicated than 

 those of the foregoing genera. The first segment is slightly clavatc, 

 longer than the seventh abdominal segment, and armed with a single 



* Plate III. Fig. 3. t Plate III. Fig. 4. t Plate III. Fig. C. 



II Plato III. Fig. 5. 1 Plate IV. Fig. 1. - Plato IV. Fig. 3. 



=< Plate IV. Fig. 4. •■ Plate IV. Fig. 5. '• Plate IV. Fig. C. 



•i Plato IV. Fig. 7. ' Pl.-*te IV. Fig. 9. " Plato IV. Fig. 8. 



