116 



Part III. — Twenty-first Annual Report 



Genus Delavalici, G. S. Brady. 



Delavalia minutissima, T. Scott, sp. nov. PI. iv., figs. 3-10. 



Description of the Female. — The female of this species resembles the 

 type-form of the genus in its general outline, and also generally in its 

 structural details, but it is the smallest of any species that has yet been 

 described, being scarcely '4 mm. (about of an inch). 



The antennules appear to consist of seven joints ; the end joint is 

 about twice as long as the penultimate one, but the others are sub-equal 

 in length, and, as usual, become gradually stouter towards the proximal 

 end (fig. 4). 



The antennae and mouth organs, being so small, were difficult to get 

 hold of, and are not figured, but so far as they could be made out they 

 resembled very closely those of Delavalia cemula (T. Scott). 



The first pair of thoracic feet resemble in some measure the first 

 pair in Delavalia robusta, Brady and Robertson, and of D. reflexa 

 of the same authors, but the principal terminal spine of the inner 

 branches is distinctly dilferent, and the spine on the inner distal 

 angle of the second basal joint is remarkably elongated, as shown by the 

 figure (fig. 5). 



The next three pairs (figs. 6 to 8) resemble those of Delavalia oemula, 

 but are more slender and moderately elongated, and while in the second 

 and third pairs the outer and inner branches are of nearly equal length, 

 the outer branches of the fourth pair are considerably longer than the 

 inner, as shown by figure 8. 



The fifth pair, though small, are, in their general character, similar to 

 those of the group to which the species belongs. The basal joint is fur- 

 nished with four setae on the broadly truncate apex ; a short and a long 

 seta near its inner aspect and a pair somewhat similar towards its exterior 

 aspect, with a distinct space between the two pairs ; the secondary joints 

 are each armed with four setae on the broadened, truncated end, the two 

 middle setae being much smaller than the others, as shown by the drawing 

 (fig- 9)- 



The caudal segments are proportionally more elongated and slender 

 than those of any other of the described species of the genus; these 

 segments, besides being very narrow, are at least equal to the entire 

 length of the last two segments of the abdomen (fig. 10). 



Eahitat. — Moray Firth ; apparently rare. No males have been 

 observed. 



Remarks. — What first attracted my attention towards this species was 

 its small size and the remarkable length of the f ureal joints. It is the 

 smallest species of the group that I have yet observed, and though 

 apparently rare, that may be partly accounted for by its being so easily 

 overlooked. The specimen from which the figures have been prepared 

 was obtained in a gathering of dredged material collected in the Moray 

 Firth several years ago, but the description of it was delayed in the hope 

 that other specimens might turn up, which would have enabled me to present 

 a more complete series of detail drawings, but this hope has not yet been 

 realised. The description and figures given here are, however, along with 

 the small size of the copepod, sufficient to distinguish it from those 

 already described, indeed, its extremely long f ureal joints would alone 

 mark it out as different, and these taken along with the peculiar armature 

 of the inner branches of the first thoracic feet, and also of the fifth pair, 

 give to the species a character distinct from other Delavalias. 



