1Q12 CRUSTACEA. 



third pair, one (the inner) is more than twice the length of the other; 

 the larger is somewhat ensiform, and is minutely serrated on the 

 margin. 



The terminal abdominal segment evidently corresponds to the fifth, 

 sixth, and seventh normal segments. The suture between the fifth 

 and sixth is distinct ; but none is perceived between the seventh and 

 sixth. 



The specimens procured from the Bonito were twenty to thirty in 

 number. They were in a fine state of preservation, though dead. 

 Excepting two or three which were dirt-brown, they were nearly 

 colourless ; the original colour could not safely be inferred. 



Genus THYROPHS, Dana. 



Abdomen ad ventrem claudens. Caput transversum. Plgmenta oculorum 

 non grandia, quatuor. Antennae 2do3 longce, sub thoracis latere 

 celatos, k-b-plicatoe, articulo lmo multo breviore quam 2dus. Pedes 

 6 postici coxis late clypeati, articulis reliquis paido abbreviati. 



Abdomen closing upon the venter. Head transverse; pigments of 

 eyes not large, often four in number. Antennae of second pair 

 long, and four to five-plicate, concealed under the sides of the 

 thorax; first joint much shorter than second. Six posterior feet 

 having the coxae broad clypeate, the remaining part of the legs a 

 little abbreviated. 



The antennae of the second pair in Thyropus, are much longer than 

 in Typhis. They are folded at each articulation, excepting the last, 

 and, may be, also at that; moreover, the first joint is much shorter 

 than the second, a fact which (as we judge from comparing them with 

 Dithyrus and Pronoe) appears to be connected with the position of 

 the antennae beneath the thorax, when retracted, instead of beneath 

 the head. In Typhis, on the contrary, these antennae are not folded 

 between the first and second joints, and the first joint is much longer 

 than the second. The general structure of the thoracic legs is as in 

 Typhis. The coxa of the fifth pair bears the following joints at or 

 near its extremity ; that of the sixth, from the under surface remote 



