14 BOVALLIUS, SOME AMPHIPODOUS GENERA. 



The femur of the fifth pair is 

 denticulated at the posterior mar- 

 gin, its lower anterior corner pro- 

 jects into a strong tooth. 



Caudal stylets slender not, pre 

 senting two rami at the ends. 



The femur of the fifth pair is 

 long, spinulous at the posterior mar- 

 gin, its lower anterior corner pro- 

 duced into a spine. 



From the fifth to the seventh 

 pair they decrease in length very 

 rapidly; the seventh being short. 



Caudal stylets slender, only the 

 last pair with a narrow short ramus, 

 articulating at its middle. 



From tlie above it is clear, that tlie name Clydonia, Dana, 

 must be rejected, and the elder name Tyro, Milne-Edwards, 

 restored. Preliminary descriptions of some new species follow 

 here, 



1. Tyro Clausii, n. sp. 



The head is thrice as deep as long. The upper antennse, 

 feebly curved downwards, reach to the anterior margin of the 

 seventh pereional segment. The epimerals distinct. The fifth 

 pair of pereiopoda are shorter than the sixth, the femur is as 

 long as the three following joints. The seventh pair are 

 longer than half the fifth. The first pair of uropoda are short, 

 not reaching to the end of the second, far from reaching to 

 the end of the third. strongly denticulated at the interiör 

 margin. The exteriör ramus of the last pair of uropoda is 

 longer than half of the coalesced interiör one. The hinder 

 corners of the pleonal segments are feebly rounded. 



Hab. The Atlantic. 



2. Tyro atlantiea, n. sp. 



The head twice as deep as long. The upper antennas, 

 feebly bent upwards, reach to the anterior margin of the se- 

 cond pleonal segment. The epimerals are distinct. The fifth 

 pair of pereiopoda are longer than the sixth, the femur shorter 

 than the three foUowing joints. The seventh pair are only a 

 little longer than a third of the fifth pair. The first pair of 

 uropoda are long, reaching beyond the end of the second, 

 very nearly to the end of the third, feebly serrated at the 

 interiör, margin. The exteriör ramus of the last pair of uropoda 

 is shorter than a third of the coalesced interiör one. The 

 hinder corners of the pleonal segments are angularly rounded. 



Hab. The Atlantic. 



