116 



74. Phyllothalestris mysis (Glaus). 



(PI. LXX & LXXT). 

 Thalestris mysis, Die freilebenden Copepoden, p. 130, PL XVIII, figs. 1216. 



Specific Characters. Female. Body moderately slender, with the anterior 

 division slightly vaulted dorsally. Integuments rather thin, and exhibiting a finely 

 squamous sculpture. Cephalic segment considerably exceeding in length the 4 

 succeeding segments combined, epimeral parts thin and pellucid, much curved 

 in the middle, and almost wholly comprising between them the oral parts ; rostrum 

 very strong, acuminate, and pointing straight down. Epimeral plates of the 3 

 succeeding segments closely contiguous and acutangular behind. Last segment of 

 metasome scarcely narrower than the preceding one, but much less deep. Uro- 

 some exceeding half the length of the anterior division, and having the genital 

 segment very large and expanded, clypeiform. Caudal rami short, quadrangular, 

 with the 2 middle apical setae much elongated and somewhat divergent, the inner 

 one about twice the length of the urosome. Eye very large and conspicuous in 

 the living animal, with 2 successive pairs of lenticular bodies, anterior extremity, 

 seen laterally, drawn out into 2 diverging lobules. Anterior antennae with the 

 distal part scarcely half as long as the proximal one. Posterior maxillipeds rather 

 slender, with the hand narrow fusiform, palmar edge straight, outer edge angular 

 in the middle, dactylus slender and elongated. 1st pair of legs with the rami 

 slender and attenuated, the outer one somewhat longer than the inner, both having 

 one of the apical claws strongly developed, falciform. Last pair of legs extending 

 almost to the end of the penultimate caudal segment, both joints greatly expanded, 

 foliaceous, the distal one oval or elliptical in form, with 6 short marginal setae 

 densely crowded together at the tip, the outermost but one very coarse, spiniform; 

 inner expansion of proximal joint extending as far as the distal joint and car- 

 rying 5 short marginal setae, 4 of which are attached close together at the bluntly 

 rounded tip, the 5th at a considerable distance from these on the inner edge. 



Male of smaller size than female, and exhibiting the usual sexual dif- 

 ferences. Last pair of legs rather dissimilar and of much inferior size, distal 

 joint narrow oval in shape, and provided with only 5 marginal setae; inner expan- 

 sion of proximal joint very slight, with only 2 unequal spines at the tip. 



Body generally of a fine rosy or light carneous colour, with the tip of 

 the urosome together with the caudal setae very dark. 



Length of adult female 1.40 mm. 



Remarks. This is an easily recognizable form and indeed one of our 

 finest Harpacticoida, distinguishing itself both by its comparatively large size and 

 the general form of the body, as also by its peculiar colour. 



