OKCUESTlDJi. Ho 



The gvQiit size of the caq)U.s and mcros of the lust ley- is due to a 

 thinning-out of the integument into a scale-like form, which is most 

 apparent upon the outer side of the leg, and, according to llatlike*, 

 increases vrith age. The muscular portion of the leg may be seen 

 upon the under suiface of the squamiform protuberance, extending 

 the whole length of the joint. 



By the aid of this enlargement the male is enabled to hold itself 

 in an upriglit position, and to walk along the siufacc of the rocks, 

 whereas the female, whicli wants this protuberance, is reduced to 

 wriggle along xipon its side, or to leap. This latter mode of progres- 

 sion it possesses in common ■with the male, using the caudal stylets, 

 which are bent under the abdomen, in the same manner as Talitrus ; 

 they arc well adapted for that purpose. The stylets are often worn 

 away bj' finction against stones. 



The posterior pleopoda resemble those of Talitrus ; the two an- 

 terior terminate in two branches each, and the posterior in one. The 

 telson is annulate, flattened, the alimentary canal passing thi'ough it ; 

 the apex is fringed with, a few fine hairs. 



In form, the hairs upon the legs and bodydiflerfrom thoseof Talitrus 

 in having a sharper extremity, with a stouter secondary appendage. 

 According to most writers, the habit of tliis animal is very similar 

 to that of Talitrus, with wliich it is said to be associated ; but 

 according to my ovm. experience, Orchestice represent the Talitri on 

 rocky, shores. I do not I'ecoUect taking Talitri except on a sandy 

 beach, nor Orchestice but upon rocky and stony groimd. I have taken 

 0. Mcditerranea in Langland Bay, Glamorganshire, under stones and 

 grass, associated "with terrestrial Isopoda, considerably above the 

 highest level of sjjring tides, though not, probably, beyond the occa- 

 sional reach of the spray. Professor Kinahan has taken them in 

 DiibUn Bay, seven feet above tide-mark, associated with Oniscus 

 murarius, 0. fossor, Armadillo vulgaris, and Porcellio scaber. 



The colour of this species is dull olive-green, incUning to bronze 

 along the back, which j-ields a metaUic lustre ; the propodos of the 

 two pairs of gnathopoda are lighter in colour, and often tipped Avith 

 briglit orange. 



We have taken the females of a light fawn-coloiu-, and so like to 

 Talitrus that we mistook them for that genus, until led to tlie dis- 

 covery of their tii;e character by accidentally examining some of the 

 dermal tissue under the microscope. 



The ova, during the process of incubation, are of a bright purple 

 colour ; Ijut the larva;, as they appear when ready to quit the pouch 

 of the mother, are of a bright orange tint. They hop vigorously as 

 soon as liberated. 



They are probably extensive in their geographical range, since 

 Rathke states ha\ing found them atTheodosia, in the C'jimea. Costa 

 has taken them on the coast of Naples, and Lucas on the coast of 

 Algeria. 



* Fauna der Krym. It cannot be ranked among the specific dinracters, since 

 it is never found in the young. 



