British Isopoda Chelifera. 329 



Thus M.-Edwards's description and figure of this limb 

 does not accord with that of either of the species we are con- 

 sidering : if acutifrons, then one of the wrist-spines is omitted ; 

 if Latreillii, then one of the spines which really belonged to 

 the wrist has been attributed to the hand. The last appears 

 to be the more likely supposition. But it may be that the 

 specimen was an abnormal one, or that A. Latreillii of 

 Milne-Edwards was another species, and neither A. Latreillii 

 of Bate and Westwood nor A. acutifrons. That it is not the 

 latter species I think we may be satisfied, for Milne-Edwards, 

 who describes the spine-formed epimeral process of the first 

 segment of the perseon, could not have entirely omitted, both 

 in his illustration and in his description, the spine-processes 

 at the anterior corners of the cephalon or those on the sides 

 of the segments of the person, which are conspicuous in 

 acutifrons but absent in Latreillii. 



Some uncertainty must remain as to whether Milne- 

 Edwards's specie? is the same as that of Bate and Westwood; 

 but it seems desirable to retain the name for the latter form 

 until this use shall have been proved to be wrong by any 

 future discovery of an Apseudes which more closely accords 

 with the figures of Milne-Edwards and found on the French 

 coast. 



The second point for consideration is what name the 

 Adriatic species described by Claus as A. Latreillii, and sub- 

 sequently identified by him with A. acutifrons, G. O. Sars, 

 ought to bear. Unquestionably the form is remarkably near 

 to that described by Sars, and to this Claus would assign it 

 as a local variety. It differs, however, in some important 

 details, chiefly in the armature of the hand of the second 

 gnathopods. This in A. acutifrons is furnished with four 

 long acute spines, but in the Adriatic form with six 'such 

 spines. 1 have examined forty specimens of the former, 

 taken by myself at Naples, and six of the latter, given to me 

 by Professor Claus ; every Neapolitan example had the four 

 spines and each of the Adriatic specimens six. Now the 

 spines which are in this position I have found in all the 

 Apseudidse examined by me to afford valuable specific 

 characters, and the number in each species to be remarkably 

 constant. There are other minute differences between the 

 two forms; thus, the outer ramus of the uropods in A. acuti- 

 frons is two-jointed, but in the Adriatic form three-jointed. 

 These two forms, however, agree in a very important 

 character, and differ from other species referred to the genus 

 Apseudes, inasmuch as the eye-lobes, which are usually 



