EUCHLANID^E. 91 



Euclilanis dilaiata . . . Moxon, Trans. Linn. Soc. vol. xxiv. 1864, p. 459, with figs. 

 Eckstein, Sieb. u. KUll. Zeils. xxxix. 1883, p. 385, fig. 33. 



SP. CH. Lorica a broad oval; dorsal plate depressed in front, arched behind; 

 transverse section (through the highest point) a low circular segment; dorsal occipital 

 edge with a broad gap, joined to the head Inj a membrane; hind dorsal edge notcJied; 

 ventral plate flat ivith a broad flange of oval outline; trophi with five teeth in each 

 uncus. 



This species, like that which precedes and that which follows it, has no occipital 

 notch in the dorsal plate, but has a broad gap (fig. 5a), which is only visible when the 

 head is completely withdrawn. The edge of the gap is united to the head by a softer 

 continuation of the lorica, which effectually obliterates the gap when the head is 

 protruded. The lorica, though depressed, slopes upwards a little to a point not far 

 from the top of a posterior notch in it, and then drops abruptly as if pinched in on 

 either side of the notch. The ventral plate is nearly as wide as the dorsal, and a ventral 

 view shows the edge of its flange running parallel to the edge of the dorsal plate just 

 within it. A side view shows the two edges as two parallel lines near together, and 

 drawn along the animal's side from end to end. Ehrenberg says that there are no setae 

 on the foot, but both Dr. Moxon and Herr Eckstein draw a pair of pedal setae, and I 

 have met with specimens bearing setae in no other respect differing from those that 

 lacked them. Dr. Cohn (loc. cit.) gives a full description of the male. It is a reduced 

 copy of the female with a sperm-sac and penis taking the place of the alimentary canal 

 and mastax, which as usual are entirely wanting, Dr. Colin has seen the wand-like 

 spermatozoa " swarming" in the sperm-sac. 



Length. Female, T \j-, male, -^ inch. Habitat. Clear ponds and ditches : common. 



E. MACRURA, Ehrenberg. 



(PL XXIII. fig. 6.) 

 Euclilanis macrura . . . Ehrenberg, Die In/us. 1838, p. 4G3, Taf. Iviii. fig. 1. 



SP. CH. " Closely resembling E. dilatata; lorica a narrower oval ; toes somewJtat 

 longer ; trophi with seven teeth in each uncus ; a pair of recurved setae on the foot." 



I have met with an Euchlanis, whose figure is given in fig. 6, which had all the 

 above characteristics given by Ehrenberg, but I doubt whether E. macrura is a good 

 species, as none of the corresponding characters seem constant in E. dilatata, except the 

 number of teeth in each uncus ; and, unfortunately, I found several specimens, of what 

 I should otherwise have termed E. macrura, with only five teeth in each uncus. 



Length. About ^ inch. Habitat. Clear ponds and ditches : not uncommon. 



E. TRIQUETRA, Ehrenberg. 

 (PL XXIII. fig. 4.) 



Euclilanis triquctra . . . Ehrenberg, Die Infus. 1838, p. 4G1, Taf. Ivii. fig. 8. 

 Hudson, Hon. Micr. J. viii. 1872, p. 97, pi. xxviii. 



SP. CH. Lorica oval, with a high flat median plate at right-angles to the dorsal 

 surface; transverse section (through the highest point) triangular; dorsal occipital 

 edge notched; hind dorsal edge notched ; ventral plate concave, and (with its flange) 

 two-thirds of the width of the dorsal plate ; trophi with five teeth in each uncus. 



This most beautiful species is often to be found among the confervoid growth on the 

 walls of old ponds. Its lorica rises in a high thin plate, and is not unlike a delicate glass 

 dish-cover set over an inverted glass dish somewhat narrower than itself. The vertical 

 plate, that thus rises like a crest from the dorsal surface, is very flexible and elastic, and 

 can be easily bent aside by the compressorium without injury. The ventral plate is 

 curved downwards all round its edge, so that the lateral furrow between the two plates is 

 wide ; and, as shown in fig. 4Z>, its flange stretches barely half-way across the base of 



