2 Mil. SPENCE BATE OK THE IMPORTAKCE OE EXAMINATION 



termination of the tail is like that of a fish, as in the Macrura. 

 In the adult, the internal antennae possess short flagella and com- 

 plementary appendages, such as exist in the order Brachyura, 

 whilst the external antennae have the long and slender flagella 

 proper to the Macrura. The scale, however, commonly appended 

 to the external antennae in the latter order is wanting, a circum- 

 stance which exhibits a relation to the Brachyura. 



An examination of the legs shows that the coxae are fused with 

 the thorax, as in the Brachyura, and not articulated with it as in 

 the Macrura, whilst, on the other hand, the posterior division 

 and caudal termination approach the Macrural type more nearly 

 than that of the Brachyura, the animal thus assuming a cha- 

 racter intermediate between the two orders. 



But in the description of the several species of the genus Gala- 

 tJiea, a peculiar difficulty appears to arise, originating in the affinity 

 which they bear to each other. So close, in fact, is the approxi- 

 mation, that the descriptions of the best writers will scarcely avail 

 for the distinction of the individual species without the assistance 

 of figures. This arises from the fact that the general characters, 

 upon which the descriptions are based, vary, in this genus, only in 

 their comparative degrees of development. 



In the three species recognized in Professor Bell's work on the 

 British Crustacea, it will be found that each species retains the 

 same characters in greater or less degree. 



Galathea strigosa is peculiar for the spinous character of the 

 carapace and cheliform legs. Every spine, however, is repeated 

 in both the other species, only less developed. We. find the 

 rostrum furnished with four lateral teeth on each side, a character 

 which also exists in each of the other species ; and although close 

 observation may detect a slightly different arrangement in the 

 relative position of these teeth, the differences are not of sufficient 

 importance to enable a naturalist thence to derive a specific dis- 

 tinction, unless the peculiarity is seconded by some more unqua- 

 lified character less liable to be affected by any peculiarity of 

 condition. 



In order to arrive at more certain residts in the identification 

 of species, we think that the microscopic examination of the sur- 

 face of the integument will be found peculiarly useful. 



This mode of examination of species may also be applied to a 

 considerable extent throughout the Crustacea generally with great 

 advantage ; and if found valuable in recent, there can be no doubt 

 that it will prove of far greater importance in extinct forma, where 



