362 Transactions of the Society. 



I have seen this form only from Woolston Pond, and only on one 

 occasion. (Plate YIII. fig. 1.) 



2. Cathypna diomis. Generally, hke C. luna, but lorica ranch 

 elevated behind, and ending there abruptly ; followed by a wide hemispheric 

 joint : toes shghtly blade-shaped ; claw two-shouldered, short, recurved. 

 Length of lorica 1/260 in. ; total, expanded, 1/150 in. Lacustrine. 



A rather remarkable little form. The carapace, broadly ovate, is 

 unusually arched, and abruptly truncate just behind its greatest eleva- 

 tion ; whence another wide rounded plate descends, as if to make the 

 carapace two-jointed.* The foot, narrow, but a little widened at its end, 

 just protrudes from under this plate, and bears the toes, jointed to it with 

 small round condyles. They are almost rod-shaped, but there is a hardly 

 perceptible curvature of their lateral margins. But the most noteworthy 

 feature is that hath the lateral margins of each toe are abruptly shouldered ; 

 and the little claw-like remainder has the acute tip recurved {d). The 

 mallei are long, strongly elbowed, and unusually slender. An eye, of 

 moderate size, richly coloured, lies far down in the occiput. The dorsal 

 plate is coarsely tesselated, as in C. rusticula. Several specimens have 

 occurred in water sent to me by Mr. Hood, from Black Loch, near Dundee. 

 (Fig. 2.) 



3. Cathypna latifrons. Lorica broadly ovate, the frontal edges 

 little diminished, both straight ; the occipital much wider than the 

 pectoral: toes broadly blade-shaped, much produced, not shouldered. 

 Length of lorica 1 /260 in. Lacustrine. 



Another of the rarities of the prolific Black Loch. The outHne 

 is that of C. rusticula, if we suppose the anterior fourth of the lorica 

 to be cut off transversely. But the ventral plate is less in area, all 

 round, than the dorsal, especially forward, narrowing more rapidly, and 

 terminating lower down. There is a considerable rounded boss behind, 

 as in both the preceding, below (or within) which are the foot-joints, 

 but not protruded. The toes have the inner edge straight, and the outer 

 much outcurved ; so that, when they are held in contact (as they 

 usually are), the pair present an outhne widely fusiform. Then the 

 points are drawn out to great length and tenuity, with an efiect very 

 pecuhar. The front of the lorica forms two stifi" lateral points ; within 

 which the margins, both occipital and pectoral, seem to be thinned-off 

 to very delicate membranes, so as to be capable of extension and retrac- 

 tion. "When closed, the occipital edge is, 1 think, straight from point to 

 point, and concave inward. Then the pectoral edge is appressed to the 

 concave dorsal surface {hut at a loiver, i. e. a hinder, level) ; and that so 

 close as to be indistinguishable from it, even by most careful focusing 

 with high powers. The internal organs seem normal. (Fig. 3.) 



4. Diaschiza glohata. Body sub-pyrifonn, becoming globose in contrac- 

 tion : front round, girded by a prominent ring : lorica dorsally cleft by 

 a wide, but shallow furrow, whose edges rise to slight ridges : foot stout ; 

 toes slender, produced, acute, slightly decurved. Length 1/200 in. 

 Lacustrine. 



The shallow dorsal cleft, having a V-shaped section, is well seen, as 



* This represents the " shelly boss " of the ijrcceding species, and may possibly be, 

 structurally considered, the basal joint of the foot abnormally developed. 



