AMPHIPOD GENUS LEPTOOHEIRUS. 673 



still on the bottle — " Protomedeia guttata Gr. m. Eiern, Lorenz, 

 Val Cassione fijl." It is a female, 5-5 mm. in length from the 

 tip of the rostrum to the tip of the telaon, with the pigmentation 

 still vivid after 48 years in alcohol. I have described this 

 specimen in detail, the account of the specific characters given by 

 Grube not being sufficiently adequate for the present system of 

 classification. In the figux^e of the whole animal it must be noted 

 that as all the appendages were drawn in situ, the exact 

 measurements and proportions of the joints of the perasopods 

 cannot be expected. Each character is compared with Chevreux's 

 specimens of tricristatus to prove the identity of the two forms. 



Description. 



Body (PL XVIII. fig. 1) more stoutly built than in pilosus and 

 pectinatits, and sideplates shorter in proportion than in those 

 species. 



Head longer than the 1st and 2nd pei'ason-segments taken 

 together ; lateral corners not prominent, rounded. 



Eyes round, black or brownish-black in colour ; ommatidia large. 



Sideplates 1-5 subequal to each other in length. Sideplate 



1 not covered by sideplate 2 ; produced forward over the side of 

 the head, of equal width throughout ; inferior mai-gin obtvisely 

 rounded, with 3 or 4 stiflf, sparsely feathered setae inset ; hind 

 margin, as in the type species, not cpntinuous proximally. Side- 

 plate 2 the largest, a little expanded distally, front angle and 

 inferior margin rounded, hind margin straight ; inferior margin 

 fringed with a row of flexible, finely plumose set*. Sideplates 

 3 and 4 alike in form, deeper than broad, slightly wider proximally ; 

 sideplate 5 with the anterior lobe about as deep as preceding 

 sideplate, but not as wide ; inferior margins of all three carry a few 

 setae, similar to those on sideplate 1. Sideplates 4 and 5 small. 



Pleon. — Segment 3 much the largest, as long as segments 1 and 



2 taken together. The 4th segment has the armature chai\acteristic 

 of this species ; the posterior margin is pi-oduced in 3 processes, 

 the median one upstanding, acute, shorter than the lateral ones ; 

 the latter broad at the base, much produced over the succeeding 

 segments, apices acute, curving vipwards, with a spinule inset in 

 each. Segments 5 and 6 are small, the posterior mai'gin of the 

 5th with a few setules dorsally. The hind margin of the 2nd 

 epimeron is straight, with 1 crenulation and setule at the postero- 

 lateral angle ; inferior margin densely fringed with long plumose 

 setae. The hind margin of the 3rd is produced and rounded, with 

 2 indentations, a setule in each ; inferior margin lightly concave, 

 with 3 long plumose setse inset midway, and 3 short spines near 

 the antero-lateral angle. 



Antenna. Superior Antenna{B.gs. 2-4). — 1st jointof the peduncle 

 stovit, shorter than the 2nd ; 3rd not quite half the length of the 2nd. 

 Primary flagelhtm 7-12-jointed, the largest female had 11 joints ; 

 accessory Jiagellum 2-3-jointed. I must note here an occasional 



Proc. ZooL. Soc— 1911,No. XLI. 41 



