82 THE ROTIFERA. 
D. compressa, Gosse. 
(Pl. XXII. fig. 8.) 
Diplax compressa . : Gosse, Ann. Nat. Hist. 2 Ser. vol. viii. Sept. 1851, p. 201. 
[SP. CH. Body much compressed ; lateral outline of lorica nearly a parallelogram. 
The lorica consists of two trapezoidal plates, of which the ventral is the longest side, 
connected together a little within the dorsal edges, so as to leave a double ridge. The 
plates are bowed outward, laterally, and seem to be conjoined below. The whole lorica 
may be rudely compared to a cell made by two spoon-bowls soldered edge to edge. The 
transparent dorsal ridges can approach and recede, and are probably connected merely 
by elastic skin. The whole frontal region is occupied by the brain, which descends sac- 
like into the occiput, but shows no trace of eye. The mastax is small, and the trophi 
obscure. A digestive canal, very wide at its origin, almost opaque from granulation, 
diminishes, with no apparent constriction, direct to the cloaca in a straight course. 
The ovary was normal, and I saw an ample contractile vesicle of sluggish action. 
No lateral vessels were traced, but one vibratile tag was seen. Along the line which, 
in the lateral view (fig. 8), indicates the bottom of the dorsal cleft, there are seen three 
oval scars, possibly insertions of muscles for closing the valves. The foot consists of 
three lengthened joints, two of which are decidedly condyliform (as in Dinocharis), 
habitually protruded; it carries two divergent toes, straight, rod-like, acute. 
The manners of the single specimen found were much like those of Salpina, but it 
swam more, rarely resting on its toes. It was found among the sediment in the phial, 
after several days’ keeping.—P.H.G.] 
Length. Of lorica, ;4, inch; total, when rotating, +}, inch. Habitat. Leamington 
(P.H.G.): rare. 
D. tTRIGONA, Gosse. 
(Pl. XXII. fig. 9.) 
Diplax trigona fi ° -  Gosse, Ann. Nat. Hist. 2 Ser. vol. viii. Sept. 1851, p. 201. 
[SP. CH. Body triangular in section ; lateral outline of lorica ovate. 
There is much resemblance between this and the preceding; but the ventral side is 
flat, and about equal to each of the lateral sides; and the longitudinal outline of the back 
forms one third of a circle. The pectoral edge, which in D. compressa is but slightly 
notched, is in trigona indented with a broad and deep sinus (fig. 9). The neck-tube 
which incloses the head is only so far retractile, that, when its sides are brought together, 
they protrude between the lorica-edges, in form of a thin fold (fig. 9a). The frontal 
cilia are strong and bristle-like, grouped on prominences; behind which a very small 
brain-sac descends, with no visible eye. The trophi, of the common Salpina pattern, 
and the internal structure generally, are as in the preceding; almost always obscured 
by a vast aggregation of air-bubbles. A thick tortuous vessel runs down each side. 
The toes are very slender, straight rods, in some examples much longer than here 
figured. The surface of the lorica is delicately punctured.—P.H.G.] 
Length. Of lorica, +45 inch; total, ,4, inch. Habitat. Leamington; Stratford 
(P.H.G.): rare. 
Genus SALPINA, Hirenberg. 
[GEN. CH. Lorica an oblong box, furnished with spines, but widely open at each 
end, split down the back; head and foot protrusile ; toes furcate, long, straight ; trophi 
sub-malleate ; eye single, cervical. 
A homely illustration of this common and well-marked genus may be obtained by 
supposing a Notommata or Diglena of long straight toes inclosed in a transparent shell. 
This shell, the lorica, may be compared to a pillow-case, open at the two ends, with one 
