542 THE VOYAGE OF H.M.S. CHALLENGEE. 



or absence of the supraorbital teeth, as for instance Alpheus crinitus, Dana, appears to 

 differ only in this respect from Alpheus minus, Say. The one was obtained amongst 

 the islands of the Eastern Archipelago, and the other on the western coast of America. 



Alpheus edwardsii (Audouin) (PL XCVII. fig. 1). 



Athanas edwardsii, Audouin, Planches de la description de l'Egypte par M. Savigny, Crust,, 



pi. x. fig. 1. 

 Alpheus edwardsii, Dana, U.S. Explor. Exped., Crust., p. 543, pi. xxxiv. fig. 2a. 



n „ Heller, Crust. Fauna des Kothen Meeres, p. 267. 



n ,, Norman, Ann. and Mag. Nat. Hist., vol. ii. p. 173, September, 1868. 



Our specimens correspond with those of Dana from St. Iago. Cape Verde Islands, and 

 a°ree with Audouin's figure more closely than with the description of Alpheus edwardsii 

 given by Milne-Edwards, which is a Mediterranean form described by him as having the 

 anterior margin of the orbital lobes armed with a small spine or tooth. 



The frontal margins above the eyes are smooth, rounded, and without a supraorbital 

 tooth, projecting nearly to the extremity of the rostrum. 



The first pair of pereiopoda has the left hand the larger, the posterior portion is 

 smooth, the anterior suddenly constricted, the pollex is short, curved, and pointed, and 

 the dactylos broad and flat, rounded on the outer side and straight on the inner, forming 

 in section an almost perfect semicircle. The right hand is long and slender, having the 

 fingers nearly as long as the rest of the propodos. The third pair of pereiopoda is with- 

 out a tooth on the infero-distal angle of the rueros. 



The males of our specimens are all about one-third smaller than the females. The 

 side on which the larger propodos occurs varies, some having it on the right side instead 

 of the left, but those that have it on the left are proportionally more numerous. 



Among those procured at the Cape Verde Islands were numerous small specimens, 

 which from their general appearance I take to be half grown individuals of this 

 species, but besides these immature forms there were numerous others, the females of 

 which were gravid with ova, so closely resembling the small individuals that they could 

 only be separated by close observation. These all have the anterior margin of the 

 orbital lobes armed with a small tooth, and correspond very closely with Milne-Edwards' 

 description ; they differ, however, from Alpheus megacheles (PL XCVII. fig. 4) which I 

 suppose to be that which the distinguished European carcinologist believed to be the 

 same as Alpheus edwardsii (Audouin). 



The females attain the length of 25 mm. or more, though they reach maturity and 

 become gravid when very small, and even at only half that length, but I have not met 

 with a male that was more than 13 mm. long. 



1 Milne-Edwards, Hist. Nat. Crust., torn. ii. p. 352. 



