368 AMPHIPOUA ABEBRANTIA. 



segments of the pereion. Three posterior pairs of pereiopoda 

 short and robust. 

 Length ^ths of an inch. 



Hah. Coasts of the United States {Say). 



The figure and description are taken from specimens presented by 

 the founder of the species to the British Museum. They appear to 

 me to be only the young of C. ovalis. 



6. Cyamus erraticus. 



Cyamus eiTaticiis, Roussel, Ann. Sc. Nat. i. (2 silr.) pi. 8. f. 24. 

 Edtcarch, Hist, ties Crust, iii. p. 113. 



This species appears to differ from C. ovalis in having but one 

 large obtuse tooth, placed near the middle of the palm of the second 

 pair of gnathopoda, and in the branchiae consisting of one long and 

 one very short branch to each organ. 



Length ^ an inch. 



Hab. Beneath the fins of Balcence. 



7. Cyamus Thomsoni. (Plate LVIII. fig. 5.) 



Cyamus Thomsoni, Gosse, 3Iarnie Zool. i. p. 131. f. 225; Ann. Nat. 

 Hist. xvi. 



Cephalon triangular. Third and fourth segments of the pereion not 

 so wide as the second. Antennae shorter than the cephalon. First 

 pail' of gnathopoda as large as the second, and similarly formed. 

 Second pair of gnathopoda not larger than the pereiopoda. 

 Branchiae short, single-branched. 



Length ^ijths of an inch. 



Hah. On the Dolphin, British Seas {Oosse). 



