PIIILODINAD^E. Ill 



a yellowish-green cellular mass, a broad pyriform ciliated stomach, narrowing gradually 

 to a bent intestine, and again widening into a broad and richly ciliated cloaca. No 

 salivary or gastric glands have been seen. There is a large irregular contractile vesicle, 

 with a period of about thirty seconds, and two very small lateral canals ; the vibra- 

 tile tags, however, have not been made out. The dorsal antenna is large, and divided 

 into three lobes at its tip, but no setse were visible. No eyes have been seen either in 

 the adult or young. [I found several examples in June 1885, on the thoracic limbs of 

 Gammarus pulex. To Mr. Giglioli's interesting details I have little to add. He says 

 that out of 700 or 800 Gammari, he had not found one free from these Callidince. My 

 experience is not quite confirmatory of this constancy. Out of four Gammari, I found 

 Callidina on only one. They adhered to its limbs merely as other Bdelloids do to any 

 surface. The " suckers," mentioned by Mr. Giglioli, are no organs of special function, 

 connected with parasitism, but are the three truncate toes common to the whole order. 



My examples, four in number, crawled off their nurse presently, on the subjection of 

 the latter to pressure in the live-box, and moved actively about in the free water ; con- 

 tracting, and elongating, and readily swimming. Their hue was a pale straw-yellow, 

 becoming clear ochre-yellow in contraction, which deepened to umber in the middle of 

 the alimentary canal, and in the maturing ovum : but of a glassy translucency. The 

 pair of spurs at the bottom of the penultimate joint of the telescopic foot, are stout, 

 thick, long and pointed. It is difficult with creatures so extremely variable in outline 

 to give any measurements which are not too vague to be distinctive : yet, as compared 

 with these organs in C. bidens, I may say that in C. parasitica they are as long as the 

 diameter of the penultimate joint itself, when thickened to its utmost by retraction ; 

 whereas in C. bidens their length does not equal half the width of the joint in the same 

 condition. Their bases are separated by a horizontal space equal to their own breadth 

 (fig. 9d). The joint itself is closely and minutely fluted. P.H.G.]. 



Length. Up to ^V inch. Habitat. Parasitic on Gammarus pulex and Asellus 

 vulgaris (Mr. H. Giglioli ; P.H.G.). 



C. BIHAMATA, GoSSB, Sp. nOV. 



(PI. X. fig. 7.) 



[SP. CH. Frontal column bearing two hooks, mutually crossed. 



This species I found in the sediment of a phial of water that had been standing on 

 my study table for more than a month, originally sent to me by Mr. H. Davis, dipped by 

 him from a pool near Snaresbrook in June 1885. 



It has not any obvious peculiarity to distinguish it from its congeners, except that the 

 column is terminated by a pair of acute hooks, set on the same plane, and crossing each 

 other transversely, like the blades of a pair of shears. These at first sight suggested 

 the C. vaga of the friend to whose kindness I had been indebted for this stranger. A 

 moment's observation showed that it was not that species, now elevated by Dr. Hudson 

 to the rank of a genus, Adineta. Yet the peculiar structure in question may well be 

 considered as a marked approach to it. Minute hooks, terminating the column, are, 

 indeed, common to all the species of the Bdelloida, but usually soft, obtuse, decurved, 

 and single. The whole trunk, somewhat swollen, is strongly scored with longitudinal 

 folds of the skin ; a dozen or more in number. The double corona was readily expanded, 

 and the animal glided freely and swiftly through the free water. It is small, as in 

 Callidina generally : the column with its terminal hooks was projected (or rather not 

 retracted) during the coronal rotation. The dorsal antenna is placed unusually far 

 back (see fig. la) ; it is small, obtuse, oblique, connected with a dorsal tubercle ; not 

 seated on it, but, so to speak, leaning on its front slope. It is scarcely in advance of 

 the mastax, when this is in its normal position. I did not see on it either cilia or setae- 



Length. Estimated at about T V inch. Habitat. Pool near Snaresbrook (P.H.G.). 

 P.H.G.l 



