HARDWICKE'S SCIENCE-GOSSIP. 



77 



the front, the lorica rises into a sharp ridge, which is 

 continued along the centre of the dorsum as far as 

 the posterior angle and gracefully arched. A delicate 

 milling is visible just within the edges of the lorica 

 and of the dorsal ridge, being most apparent near 

 the posterior angle and dying away after passing the 

 lateral angles and the crest of the ridge. It is easily 

 distinguished from M. rhomboides, the dorsum in 

 that species being tectiform, not ridged. 



The head is furnished with the usual plate : two 

 eyes are distinct and a minute pimple-like antenna is 

 visible in a side aspect. The internal organs are 

 very delicate, and I have not yet succeeded in tracing 

 out the gastric glands and the contractile vesicle. 

 In 1 several specimens the ovary was well developed, 

 and in addition a large egg was conspicuous in the 



Fig. 42. — Ventral aspect of Metopidia rhomboidula. 



body cavity. The foot and toes appear to be normal 

 in structure. Length, about 5 fo inch. 



Some six or seven specimens have occurred in 

 some stock jars, containing anacharis, conferva; and 

 watermoss from a very prolific ditch near the Lea. 



The same ditch has repeatedly furnished specimens 

 of M. rhomboides, triptera and oxy sternum, all so- 

 called rare species, in addition to the common 

 M. kpadclla, bractea and solidus. M. acuminata, 

 has also occurred, but is in my experience the most 

 rare of those named. The present species appears 

 more given to swimming than its congeners, and I 

 have but seldom seen it gliding over conferva; or on 

 the glass sides of my troughs. My sketches are from 

 the last specimen found, which I succeeded in 

 mounting in fair condition. Allowance is, however, 



to be made for undue protrusion of the head and 

 neck, consequent upon the swelling of the body, 

 before the preservative solution employed had 

 stiffened the membranous integument and muscles. 

 I have not been able to secure such a sketch as 

 would enable me to give an accurate transverse 



Fig. 43. — Section through Metopidia rhomboidula. 



section, but I believe that shown in fig. 43 to be 

 nearly correct. 



In this species, at all events, the milling above 

 referred to appears to have no connection with that 

 faint wavy line visible in most specimens of Meto- 

 pidia, which indicates either the line of fusion of 

 the plates of the lorica, or the edge of the lining 

 membrane. 



2. — EUCHLANIS SUBVERSA. 



Spec. Char. — Lorica broadly ovate ; ventral plate 

 considerably larger than dorsal, the sides much bent 

 upwards ; dorsal plate of similar outline, nearly flat, 

 but having a central longitudinal depression, save 

 near anterior margin where it rises to a slight con- 

 vexity. Both plates anteriorly truncate, straight or 

 slightly excavate, dorsal occipital edge joined to head 

 by a membrane. Foot apparently without seta;, 

 toes long, of uniform thickness, slightly out-curved. 



A single specimen of this handsome species was 

 found on 2S September in a gathering from the ditch 

 referred to in preceding description, and was, after a 

 long interval, followed by a second about the end of 

 December. 



The sketch (fig. 44) made from life, of the earlier 

 specimen, will be found on comparison, very like 

 indeed to the figure in Hudson and Gosse's Rotifera 

 of the dorsal view of Diplois propatula, but the 

 characters presented by my specimen differ very 

 materially from those assigned to that species. 



The present form is, as I have desired to indicate 

 by the specific name, an Euchlanis upside down. 

 For not only is the ventral plate considerably the 

 larger, but it is also strongly turned upwards at the 

 sides, forming a rounded keel, and the dorsal plate, 

 smaller but of similar ovate outline, is at its occipital 

 edge slighly arched for the protrusion and retraction 

 of the head, but immediately behind sinks in a 

 shallow longitudinal depression. 



The plates are separated by a broad and deep 

 sulcus, and held together by a stout membrane. 



