416 SPH^ROMID.E. 



followed by a slender nine-jointed flagellum. The lower 

 antennae are slender, having the four basal joints slender, 

 the first and second shorter than the third and fourth, 

 which are equal. The flagellum is slender, and consists 

 of seventeen articulations. The foot-jaws differ from 

 those of the typical species, in having each of the three 

 intermediate joints dilated into an internal flattened lobe, 

 a character which, in conjunction with that of the short 

 plates of the lateral appendages of the terminal segment 

 of the body, seems to indicate a more than specific 

 distinction, and wliich is probably also found in Sph. 

 Griffithsii, which appears to be congeneric. The five pos- 

 terior segments of the body have their lateral portions 

 separated by a slender impressed line (indicating the basal 

 division of the legs attached to each of them), and the 

 hind segment of the tail is marked with two elongated 

 carina? ; its extremity is obliquely rounded, with a small 

 notch on either side. 



We regret that the paucity of individuals which we 

 have been able to examine of this and the preceding 

 species, and its supposed variety Sph. Griffithsii, do not 

 allow us so satisfactorily as we could have wished to 

 determine the real position of the latter, which may pos- 

 sibly belong to the present species, having the tubercles 

 on the tail nearly obliterated. 



Dr. Leach obtained his unique specimen from Mr. C. 

 Prideaux, who took it on the west coast of Devonshire. 



We possess a specimen of the species of Sphceroma 

 figured by Savigny in the great work on Egypt. Crust, 

 pi. 12, f. 4, distinguished from Sph. serratum by its more 

 elongated form, flattened triangular head, and especially 

 by the semicircular notch at the extremity of the tail. 

 We believe it to be British ; but being unable to speak 

 with precision on tlie subject, we have omitted to figure 

 it in the present work. 



