92 



segments being not wide apart at the lateral margins, and 

 by the possession of two slender filiform branchiae at- 

 tached to each side of the third and fourth segments of 

 the body. The species represented by Mr. Spence Bate 

 (Plate 58, fig. 3) is from the Cape of Good Hope, and 

 possesses a very strong tooth near the extremity of the 

 fourth joint of the second pair of legs. We presume, 

 notwithstanding its locality, that it is identical with 

 M. Roussel de Vauzeme's species. The branchial ap- 

 pendages of the males are longer than those of the 

 females. In the species before us the anterior pair are 

 furnished at the base with a single pointed appendage, 

 whilst the posterior pair have this appendage doubled, its 

 branches being rather unequal in size ; these appendages 

 exist in the female in the modified form of large flat- 

 tened plates, or valves, extending beneath the middle of 

 the body. These plates are concave, pedunculated, 

 fringed at the edges, and formed of a double transparent 

 membrane : thus constituting a sac without an external 

 orifice. These plates, lying upon each other, serve as a 

 pouch, within which the eggs are deposited, and the 

 young hatched. Some uncertainty has been entertained 

 as to the real nature of the branchial appendages, which 

 have been regarded as simple stems, false legs, pseudo- 

 branchiae, vesicles without determinate use, and organs of 

 respiration ; but the direct observation of M. Roussel 

 on the living animals has demonstrated that they are 

 branchial canals in communication with the dorsal vessel, 

 and of a membranous texture, whilst the appendages at 

 their bases in the male are differently organized, being 

 crustaceous, and unfitted for organs of respiration ; and 

 the plates of the ovigerous pouch in the female are also 

 destitute of branchial canals, and consequently unable to 

 perform the functions of gills. 



