114 THE ROTIFERA. 
narrower. The foliations are so slight as to permit the lateral antenne with their 
nervye-threads to be easily seen. Their rocket-shaped extremities lie close to the lorica, 
not far from its edge, and between the first and second bosses on either side: they are 
therefore, in an unusually forward position. The lateral canals can also be traced, 
in many conyolutions, from the lower part of the head, to the point where they are 
abruptly cut off by the gastric glands. In young specimens, in which the ovary is a 
small, transverse, pyriform sac, and so does not obscure the view, they are seen again 
below the gastric glands on either side of the stomach; and, passing behind it, appear to 
end below it on either side, in small pear-shaped expansions. I could never find any 
contractile vesicle; but, under favourable conditions, I have seen three pairs of 
vibratile tags: one a little above the heads of the gastric glands, one on a leyel with 
the middle of the stomach, and one not far from the pear-shaped sacs in which the 
lateral canals seem to end. 
Length. Lorica, ;3, inch. Habitat. Abbot’s Pond, Clifton (C.T.H.) : not common. 
Abundant near Torquay (P.H.G.). 
I met once with an empty lorica (Pl. XXVI. fig. 17) which I suppose to be that of 
Ehrenberg’s P. elliptica. It came from a pond in Sutton Park, Birmingham. 
P. mucronata, Gosse, sp. nov. 
(Pl. XXVI. fig. 15.) 
[SP. CH. Lorica usually circular; dorsal plate furnished with an acute mucro 
projecting from its front. Lacustrine. 
In April 1885, associated with P. patina and P. valvata, which were swarming in 
one of my window reservoirs, I first met with this very pretty form. It never became 
very numerous; but, in the course of a few weeks, during which I was paying special 
attention to the genus, I met with more than thirty examples. The thought occurred 
that it might be the young condition of one of its larger fellow-species ; and, if so, valvata 
would be the more probable. Yet I have found the young of valvata no larger than 
mucronata, but with no trace of the mucro: and I have seen a nearly mature egg in 
mucronata, which, though not conclusive, augments the probability of adult condition. 
On the other hand, slight unevenness of frontal outline is not rarely discernible in adult 
specimens of both the larger species. The matter is still swb judice ; but for the present 
mucronata seems worthy of specific rank. 
The lorica has not only the intra-marginal granulation of its fellows, which gives 
them so elegant a resemblance to a new silver coin, but is shagreened or studded with 
close-set rugosities over the entire surface of the dorsal plate, so delicate, however, 
that the hyaline transparency is not interrupted. What I consider the branchial organs 
are small; the efferent lobe, answering to the pyriform (gastric gland), is generally 
inconspicuous, and the afferent tubes are clustered in form of a cone around the base of 
the sub-horizontal muscle. I have not satisfactorily observed the existence of eyes. 
The pair of diagonal muscles is unusually well-developed. The lorica has about two- 
thirds of the diameter of valvata.—P.H.G.] 
Length. About 4, inch. Habitat. A domestic aquarium (P.H.G.): rare. 
P. cuyprata, Hhrenberg. 
(Pl. XXVI. fig. 14.) 
Pterodina clypeata ° © Ehrenberg, Die Infus. 1838, p. 518, Taf. Ixiv. fig. 6. 
[SP. CH. Lorica elliptical, truncate at each end; coronal disks widely separated. 
Marine. 
I first formed acquaintance with this attractive species in July 1850, in sea-water 
from the Essex coast; and lately it has been sent me in abundance by Mr. Hood from 
