ürchestia 533 



Body nither compressed. Side-plate 1 small, 2*^ — 4*'^ quadrate, the 

 small process of bind margin distinct, 5^'^ bvoad, in front nearly as deep 

 as 4**'. Pleon segment 3, postero-lateral corners quadrate. Eyes irregularly 

 rounded, black, less than the diameter apart. Antenna 1 seldom reaching 

 beyond penultimate Joint of peduncle of antenna 2, l'** Joint shorter than 

 2^ or 3^, flagellum 6— 8-jointed. Antenna 2 aboiit ^3 as long as body, 

 ultimate Joint of peduncle sometimes considerably longer than penultimate, 

 flagellum about 20-jointed. Gnathopod 1 in d, 6*'» Joint shorter than 5*^ 

 both distally widened, 6*^ usually resting on produced part of 5*^. finger 

 matching transversa palm, but not covering the produced part of 0*^ joint. 

 Gnathopod 2 in ci", 2'^ Joint channelled in front, not lobed, 5* very small, 

 ßth ijirge, widening to the palm, which is almost transversely arcuate between 

 a depression adjoining tiuger-hiuge and au obtuse detiniug projection. Gnatho- 

 pod 1 in 9 , ö**^ Joint distally widened, 6*^ narrowly oblong, the short trans- 

 verse palm overlapped by tinger. Gnathopod 2 in Q , 2'^ Joint membranaceous, 

 broader above than below, 5*^ with free hinder part bulging, 6^^ produced, 

 but not very greatly. beyond the small, rather obliquely placed finger; 

 marsupial plates rather nan'ow, long, fringed with long setae. Peraeopod 2 

 shorter than peraeopod 1, finger with sinuous inner margin. Peraeopods 

 3—5 successively longer, 2'^ Joint well expanded. Peraeopod 5 in d. 4**» 

 Joint greatly widening distally, 5*^» greatly expanded, widest near base, both 

 these joints having flattened edges before and behind, and in adolescent d 

 showing numerous gradations to the linear form fouud in 9 and youug; 

 6*^ Joint straight. üropod 1 rather long, rami shorter than peduncle, both 

 with lateral spines. üropod 3, ramus much shorter than peduncle. Telson 

 soft, thick, about as broad as long, apex slightly emarginate. Colour d 

 brownish, o greenish. L. about 17 mm. 



Xorth-Atlantic with adjoining seas (Europe, from the Baltic to the Black Sea; 

 Algiers; Madeira; Azores); ?South-Pacific (lUawarra [IVew South Wales], sea shores). 



3. O. chevreuxi Gruerne 1887 O.e. (?), Guerne in: Naturaliste, v.9 (p. 6) | 

 1888 O.e. (^ ), Guerne in : Bull. Soc. zool. France, v. 13 p. 59 f. 1, 3, 5, 7 | 1888 0. c. ((5), 

 Chevreux in: Bull. Soc. zool. France, r. 13 p. 92 f. 1, 3, 5 ; 1888 0. littorea (part.)?, T. 

 Barrois in: Bull. Soc. zool. France, r. 13 p. 19 i 1893 0. gammarellus (part.), A. DellaValle 

 in: F. Fl. Neapel, r. 20 p. 499. 



Distinguished from 0. gammarellus in d by: peduncle of antenna 2 

 longer and more robust, flagellum also more elongate (the 18 — 20 joints being 

 mostly longer than broad), gnathopod 2, 6*ii Joint more broadly oval, palm 

 much more convex, with deep groove adjoining the defining angle, finger 

 shorter and more robust, peraeopod 5 more elongate, with 4*^ and 5^^ joints 

 robust but much longer than wide, ß^^ Joint long, curved; in 9 by: antennae 1 

 and 2 longer, gnathopod 2, 2*^ Joint much less widened, 4*^ Joint carrying 

 2 spines on apex, 5**^ and 6**^ joints more elongäle, peraeopod 5 longer, 

 with very long, slightly ciu'ved 6*^^ Joint, uropods 1 and 2 longer, üropod 3 

 with much stronger spines on peduncle, telson with strenger spinules, and 

 its narrower apex much more sharply emarginate. Colour violet, almost 

 rose, deeper above. L. about 15 mm. 



Azores (Fayal, in the caldiera or crater); Teneriffe (in the forest of Las Mercedes, 

 under detritus on the banks of streamlets, not less than 500 m above sea-level). 



4. O. montagui Aud. 1826 O.ni., Audouinin: Descr. Egypte, r.liv p.93 Crust. 

 1. 11 f. 7 I 1866 O.m., Cam. Heller in: Denk. Ak. "Wien, «;.26n p.2 t. 1 f . 3, 4 i 1866 

 0. m., E. Grube in: Arch. Naturg., v.ti2i p. 380 t. 9 f. 1,2 | 1868 0. m., Czerniavski in: 



