188 





124. Stenhelia Giesbrechti (Scott). 



(PI. CXXIV, fig. 1). 



Deiavalia Giesbrechti, Th. Scott, On some new and rare Copepoda from the Clyde; Annals of 

 Scottish Nat. Hist. 1896, p. 225, PL IV, figs. 1 10. 



Specific Characters. Female. Body of the usual short pyriform shape, 

 though scarcely as robust as in the preceding species, the anterior division being 

 less dilated in front. Rostrum broadly triangular, with the apical part well de- 

 fined and slightly bifid at the tip. Urosome considerably shorter than the anterior 

 division and somewhat attenuated distally, genital segment conspicuously dilated 

 at the base, anal segment shorter than the preceding one. Caudal rami not much 

 produced, being scarcely twice as long as they are broad and rather approximate, 

 innermost but one of the apical setae slender and elongated, and conspicuously 

 ciliated in the middle, the adjacent seta on the outer side very peculiarly trans- 

 formed, being remarkably dilated throughout the greater part of its length, almost 

 sausage-shaped, and terminating in a very thin and slender hair-like lash, the 

 dilated part coarsely ciliated on both edges distally. Anterior antennae compara- 

 tively short and of the usual structure. Posterior antennae with the outer ramus 

 very slender, exceeding in length the last joint of the inner. Oral parts of the 

 -usual structure. 1st pair of legs with the outer ramus about the length of the 

 .inner, middle joint provided inside with a distinct, though rather small seta, last 

 joint a little longer and armed with 2 slender spines and 2 still longer setae; 

 inner ramus biarticulate, distal joint longer and narrower than the proximal one, 

 and provided at the tip with a slender spine and a ciliated seta, inside with 2 

 similar setae. Natatory legs moderately strong and of the usual structure. Last 

 pair of legs with the distal joint oblong quadrangular in form, carrying on the 

 somewhat obliquely truncated end 5 setae, the middle one being very small, hair-like; 

 inner expansion of proximal joint rather slight and subangular inside, carrying 4 

 slender ciliated setae, the 2 outermost ones smaller than the other 2, and arranged 

 close together. Ovisacs comparatively small and but slightly divergent, containing 

 a very limited number of ova. 



Male unknown. 



Colour whitish. 



Length of adult female 0.44 mm. 



Remarks. This is a very small form, and at once recognizable from any 

 of the other species of the genus by the peculiar transformation of the outer 

 one of the 2 middle caudal setae, as also by the comparatively small and appres- 

 sed ovisacs. 



