630 Leptocheirus, Isaeidae, Isaea 



Body more elongate and side-plates smaller than in L. hirsutimanus, 

 pleon segmeDt 4 with 3 medio-dorsal, sharp and strong teeth. Pleou segment 3, 

 postero-lateral corners strongly rounded, margin slightly crenulate. Eyes 

 small, oval, black. Antenna 1, 2*^ Joint longer than 1^*, 3"^ scarcely half 

 as long as 2<^; accessory flagellum 3-jointed. Antenna 2, ultimate Joint of 

 peduncle sh orter than penultimate. Gnathopod 1, 6*^^ Joint as long as 5*^, 

 widening to the finger, which is as long as the palm (in figure: 6*^ Joint oval with 

 scarcely defined palm). Gnathopod 2, 2*^ Joint almost as long as 3^ — 6*^^ 

 combined, setae still longer; 4:^\ 6^^ and 6*^ in leng-th equal one to the 

 other (in figure: 5^^ much longer than 4*^ or 6*^); finger slightly curved. 

 üropods 1 and 2, peduncle with strong apical spine. üropod 2, inner ramus 

 the longer, with 5 large teeth at the apex. üropod 3 very short, rami laminar, 

 outer with apical setae, inner shorter, with apical tooth. Telson prismatic, 

 strongly concave above. Colour simply yellow or with dorsal brown bands. 

 L. 7 mm. 



France (South-West of Brittany). 



L. pilosus Zadd. 1844 L. p., Zaddach, Syn. Crust. Pruss., p. 8. 



Probably identical with one or other of the species here described. L. 4 mm, 



Baltic. 



35. Farn. Isaeidae 



1853 Subfam. Isaeinae, J. D. Dana in: U. S. expl. Exp., v. 13ii p. 913. 



Side-plate 5 the largest. Antenna 1, accessory flagellum well developedJV 

 Gnathopod 2 the larger, subchelate. Peraeopods 1 and 2 not glandulär. 

 Peraeopods 1 — 5 subchelate, 3^ — 5^^ equal. üropod 3 biramous. Telson simple. 



Marine. 



1 genus with 1 species. 



1. Gen. Isaea M.-E. 



1830 Isaea (Sp. un.: T. montagui), H. Milue Edwards in: Ann. Sei. nat., u 20 

 p. 380 I 1893 L, A. Della Valle in: F. El. Neapel, u 20 p. 679 [ 1862 I., Iscoea, Bäte, 

 Cat. Amphip. Brit. Mus., p. 122; t. 22 f. 1. 



Body robust. Side-plate 5 as deep as the 4*^. Antenna 1 the longer, 

 with well developed accessory flagellum. Maxiila 1, outer plate with 11 spines 

 (Della Valle, in figure). Gnathopods 1 and 2 subchelate, 2*^ stronger. Peraeo- 

 pods 1 — 5, 6^^ Joint distally dilated. üropod 3 not elongate, rami equal, narrow. 



1 species. 



1. I. montagui M.-E. 1830 I. m., H. Milne Edwards in: Ann. Sei. nat., «.20 

 p. 380 I 1840 I. m., H. Milne Edwards, Hist. nat. Crust., v. 3 p. 26 t. 29 f. 11 | 1862 I. m., 

 Iscoea montagua, Bäte, Cat. Amphip. Brit. Mus., p. 122; t. 22 f . 1 | 1887 Isaea montagui, 

 Chevreux in: Bull. Soc. zool. France, v. 12 p. 301 | 1893 I. m., A. Della Valle in: F. Fl. 

 Neapel, v. 20 p. 679 t. 6 f. 7; t. 13 f. 30—42. 



Head, lateral lobes not strongly produced. Side-plates 1 — 5 rather 

 deep. Eyes crimson. Antenna 1, 1^* Joint a little shorter than 2^, 3"^ about 

 ^8 as longas 2*^; flagellum subequal to peduncle, 16-jointed; accessorj^ flagellum 

 6-jointed. Antenna 2, ultimate Joint of peduncle rather shorter than penultimate 

 and than the 8 — 12-jointed flagellum. Upper lip rounded. Mandible. 



