442 



Fam. Diosaccidae. 



Amphiaseus simulans (Scott). 



(Suppl. PL 54). 



Stenhelia simulans, Norm. & Scott, Copepoda new to Science from Devon and Cornwall. Ann. 



Mag. Nat. Hist. ser. 7, Vol. XV, p. 285. 



Specific Characters. Female. Body slender, sublinear in form, or slightly 

 tapered behind. Rostrum very prominent, acuminate. Urosome somewhat shorter 

 than the anterior division, last segment not quite attaining the length of the 

 preceding one. Caudal rami very short, being scarcely as long as they are broad, 

 apical setae normal. Anterior antennae moderately slender, about the length of 

 the cephalic segment, and composed of 8 joints, the 2nd much the largest and 

 exhibiting in the middle a very conspicuous constriction, 4th joint about twice as 

 long as the 3rd, terminal part exceeding in length those joints combined. Posterior 

 antennae with the middle joint of the outer ramus very small and without any 

 seta. 1st pair of legs with the outer ramus about the length of the 1st joint of 

 the inner, middle joint without any seta inside, terminal joint slightly longer and 

 armed with only 2 spines and 2 geniculate setae; inner ramus with the 1st joint 

 narrow linear in form and carrying inside, near the end, a slender seta, last joint 

 fully twice as long as the middle one, and armed in the usual manner ; both these 

 joints combined considerably exceeding half the length of the 1st. The 3 suc- 

 ceeding pairs of legs with the rami moderately slender, and the natatory setae 

 somewhat reduced in number, terminal joint of outer ramus in the 2 anterior 

 pairs having only a single seta inside, that of the inner ramus in 2nd and 4th 

 pairs likewise with a single seta on the inner edge. Last pair of legs with the 

 distal joint oblong oval in form and edged with 6 setae; inner expansion of 

 proximal joint triangular in form and extending considerably beyond the middle 

 of the distal joint, marginal setae 5 in number, Ovisacs of moderate size, oblong 

 fusiform in shape. 



Male having the anterior antennae transformed in the usual manner. 1st 

 pair of legs with the spine inside the 2nd basal joint remarkably produced and 

 somewhat sigmoid. Inner ramus of 2nd pair of legs with the middle joint expanded 

 inside to a rounded lobe, and carrying at the end outside 2 strong deflexed spines, 

 the inner one distinctly bifid at the tip. Last pair of legs much smaller than in 

 female, distal joint short, pyriform in shape, with only 5 marginal setae; inner 

 expansion of proximal joint conical in form, with 2 thickish apical setae. 



Colour not yet ascertained. 



Length of adult female 0.93 mm, 





