Mr H. Goodsir on (he Genus Citma. 123 



the inferior edge of this part, and are about sixteen or seven- 

 teen in number ; they are not laminated like those of the higher 

 Crustacea, but consist of one large piece, which is apparently 

 composed of a great number of cells. 



The organs of generation are not apparent in the male, but 

 in the female, and, especially when she is loaded with spawn, 

 these organs are at once perceptible. They are very similar 

 in their structure and appearance to the same parts in the fe- 

 male Ml/sis. They consist of four scales, which arise from 

 the inferior edge of the thoracic segments. These scales are 

 of an irregular oval shape, concave internally, and convex ex- 

 ternally, and they are overlapped by one another.* The eggs 

 are of considerable size, and of a bright straw colour. It is 

 from the genus Cuma only that these observations were taken 

 in regai'd to the organs of generation. 



When a portion of the skin, or shell rather, is placed under 

 the microscope, it presents a very beautiful appearance ; it 

 apparently consists of a great number of nuclei, arranged in 

 some degree of order. These nuclei are stellated, and here 

 and there larger nuclei may be observed, the edges of which 

 are quite smooth.! 



The structure of these animals is so peculiar, as to render 

 the assignation (at present) of a proper place in a natural ar- 

 rangement of the class, a point of very considerable difliculty. 

 This arises in a great measure, without doubt, from our very 

 limited knowledge of the class. I rather think, however, that 

 they should be ranged among the lower Dccapoda macroura. 



Genus Cuma (Edwards). 



Generic Characters. — The superior antennae are single-jointed, and scale- 

 like ; the inferior antennse are five-jointed. The caudal styles have the 

 double terminal scales biarticulate, the last of ■which is always the 

 shortest. 



Cuma Edwardsii, mihi.J 



C. — With tlie superior antennse rhomboidal ; with the ambulatory divi- 

 sion of the first pair of legs, with the first joint bent at an obtuse 

 angle ; with the thumb-like process single-jointed, and with the last 

 joints clavate. Length, 4 lines. Hab. Frith of Forth. 



Description. — The whole animal is of a fine straw colour, with a delicate 

 tinge of pink, which is brighter in certain lights ; the shell is quite 



•>- Plate IV. Fig. 12. t Plate II. Fig 18. t Kate II. Fig. I. 



