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Part III. — Sixteenth Annual Report 



curved from the somewhat narrow basal part to the broad truncate 

 extremity of the foot, where it terminates in a small thumb-like process ; 

 two setae spring from the truncate apex and one from the lateral aspect of 

 the distal half ; an elongate seta also springs from the outer angles of the 

 thoracic segment to which the fifth pair are attached (fig. 10). 



Description of the male. — The male appears to be similar to the female 

 in every respect except in the structure of the antennules, and even 

 in this respect the difference is not apparently very great. The male 

 antennules are twelve-jointed, the proportional lengths of the first eight 

 being similar to those of the female ; the ninth is considerably longer than 

 the same joint in the female antennule, while it is also of a different form, 

 and carries a long, stout seta at the distal extremity ; the last joint is 

 shorter than the same joint in the female antennule, and is hinged to the 

 preceding joint (fig. 11). 



Habitat. — Otter Spit, Loch Fyne. 



Remarks. — Two or three specimens of this somewhat curious species 

 were obtained in a gathering of micro-crustacea sent to me from Loch 

 Fyne by F. G. Pearcey, of the Fishery Board. It seems undoubtedly to 

 belong to the sub-family of Dyspontiin^e of Dr. Giesbrecht, but I am un- 

 able to place it under any of the described genera of that group. It has 

 certain points of resemblance with Myzopontius, but the structure of the 

 mouth organs excludes it from that' genus. Meanwhile I have decided 

 to institute a new genus for its reception, and as there is but one species, 

 the description includes both the generic and specific characters. 



Artotrogus wbictilaris, Boeck (PI. XIV., figs. 12-21). 



Description of the male. — Length, L34 mm. of an inch). Seen 

 from above, the thorax is almost circular, being about as broad as it is 

 long ; the segments are somewhat produced laterally into angular pro- 

 cesses. The abdomen is small and apparently only (?) three-jointed, the 

 first two being very short. Caudal stylets short and broad (fig. 12). The 

 antennules are short, and eight-jointed ; the first and second joints are 

 large, the others smaller ; an aesthetask springs from the end of the last 

 joint (fig. 13). The proportional lengths of the joints are shown by the 

 formula — 



24 • 23 • 9 • 5 • 9 • 6 • 7 • 15 

 1 • 2-3-4-5-6-7 - 8 



Antennae three-jointed and bearing three terminal hairs ; secondary 

 branches very small (fig. 14). Maxillae large, lobes unequal, outer lobes 

 elongate, broad at the base, but tapering gradually to the narrow apex, from 

 which springs a long, moderately stout, and slightly plumose seta ; inner 

 lobe about half the length of the other, and bearing three terminal setae, 

 two of which are long and moderately stout and one small (fig. 15). The 

 anterior foot-jaws are provided with moderately short but stout and 

 strongly-curved claws (fig. 16). The posterior foot-jaws are also armed 

 with stout, though short, terminal claws, the structure of which resembles 

 generally those of the same appendages in other species of Ascomyzontidse 

 (fig. 17). The first and second pairs of swimming feet are large, and 

 both branches are three-jointed ; in the first pair the marginal spines are 

 small but stout, there are no terminal spines on either the outer or inner 



