CHAP. II. THE SPECIES OF MEL1TA. 



From the structure of the clasp-forceps : 



11 



From the presence or absence of the 

 secondary flnpellum. 



M. palmata, &c. M. exilii, &c. M. Fresnelii. M, palmata, &c. M. exilii, &c. M. Fresnelii 



As, in the first case, among the Crabs, a typical agree- 

 ment of arrangements produced independently of each 

 other would have been a very suspicious circumstance 

 for Darwin's theory, so also, in the second, would any 

 difference more profound than that of very nearly 

 allied species. Now it seems to me that the secondary 

 flagellum can by no means furnish a reason for doubting 

 the close relationship of M. Fresnelii to M. exilii, &c., 

 which is indicated by the peculiar structure of the un- 

 paired clasp-forceps. In the first place we must con- 

 sider the possibility that the secondary flagellum, which 

 is not always easy to detect, may only have been over- 

 looked by Savigny, as indeed Spence Bate supposes to 

 have been the case. If it is really deficient it must be 

 remarked that I have found it in species of the ge- 

 nera Leucothoe, Cyriophium and Amphilochus, in which 

 genera it was missed by Savigny, Dana and Spence 

 Bate that a species proved by the form of the epimera 

 (coxde, Sp. B.) of the caudal feet (uropoda Westw.), &c., 

 to be a true Amphithoe 2 possesses it that in many 

 species of Cerapus it is reduced to a scarcely perceptible 



2 I accept this and all the other genera of Amphipoda here men- 

 tioned, with the limits given to them by Spence Bate (' Catal. of Amphi- 

 podous Crustacea '). 



