82 MESSES. NORMAN AND STEBBING ON THE 



anterior margin, and a strong spine on the middle of the ventral surface. The epistoma 

 is always armed with a similar spine. 



The pleon is rather narrow, the first five segments are produced laterally into sharp 

 processes and beset with long plumose hairs ; the last segment is much drawn out, and 

 is subequal in length to the whole of the rest of the pleon ; it has two small ciliated 

 eminences on each side. 



The upper antennae have the basal joint half as long again as the second and third 

 combined, with both its inner and outer margins partially serrulated ; the flagella 

 are shorter than the peduncle, the inner 6-, the outer 13-jointed. 



The first gnathopods of the female are moderately strong, scarcely less than the 

 second pair ; the hand longer than the wrist, ovate, the finger armed with a tubercle 

 near the base. The uropods are equal in length to half the animal, the peduncle 

 ornamented with many plumose setse on the outer margin ; outer branch composed of 

 seven joints scarcely equalling a fourth part of the inner branch in length. Colour white. 



Length about 6 millim. 



Montagu procured his types on a Pecten maximus at Salcombe, Devon. Spence Bate 

 has found it in Plymouth Sound, and Mr. Cocks at Falmouth. Prof. G. O. Sars has 

 taken it in the Mediterranean (Messina), and Heller in the Adriatic. 



Apseudes talpa may be known from A. latreillii (1) by the serration of the first joints 

 of the upper antennse, (2) by the spines which arm the epistoma and the ventral surface 

 of the perseon-segments, (3) by the great length of the terminal segment of the animal. 



Montagu's figure, copied again and again by various authors, is altogether mislead- 

 ing and erroneous. Milne-Edwards's figure, taken from one of Colonel Montagu's 

 specimens, though somewhat better, is quite insufficient to distinguish the species. 

 Bate and Westwood were the first to give characteristic drawings of the animal. 

 Fortunately Colonel Montagu's specimens are still preserved in the British Museum, 

 and have been kindly examined for us by Mr. Miers and compared with A. latreillii ; 

 and there can be no doubt that, as stated in the ' British Sessile-eyed Crustacea,' they 

 belong to the species to which Montagu's name is here assigned. 



The Apseudes talpa of Lilljeborg, and of the earlier writings of G. O. Sars, is not 

 this species, but A. spinosa, M. Sars. 



We have not ourselves had the opportunity of examining specimens of A. talpa, and 

 the foregoing description has been compiled from those of Sars and Bate and Westwood. 



2. Apseudes latreillii (Milne-Edwards). (Plate XVI.) 



Rhcea latreillii, M.-Edwards, Ann. des Sci. Nat. 1"" ser. xiii. p. 288, pi. xiii. a. figs. 1-8 ; id. Hist, de 

 Crust, iii. p. 141 ; Cuvier, Eeg. Anim. (edit. Crochard), Crustaces, pi. Ixii. fig. 2 ; Latreille, 

 Cours d'Entomol. p. 403; Lamarck, Anim. sans Vert. (2'™" edit.) v. p. 291. 



Apseudes latreillii, Bate and Westwood, Brit. Sess.-eyed Crustacea, ii. p. 153 ; G. O. Sars, "Revision 

 af Gruppen Isopoda Chelifera," Archiv for Math, og Naturvid. vii. 1882, p. 14. 



