132 THE KOTIFERA. 



ending in fans of imbricated setre, in the conical shape of the bod} 7 , and in the broad 

 truncate corona ; but they differ strikingly in the way in which the limbs are set on the 

 body : for in Pedalion they are arranged around it parallel to its longitudinal axis, while 

 in Hexarthra, as in the Nauplius larva, they radiate from the centre of the ventral surface. 

 Nor is this the only difference. Hexarthra's limbs are in three graduated pairs, while 

 Pedalion' s ventral limb is far longer than any of the others : moreover, Hexarthra lacks 

 two long stylate appendages, ciliated at the ends, which are to be found on the posterior 

 end of Pedalion' s dorsal surface. 



Genus PEDALION, Hudson. 



GEN. CH. Limbs arranged round the body in pairs, and parallel to its longitudinal 

 axis ; tivo stylate, ciliated appendages on the posterior dorsal surface. 



P. MIRUM, Hudson. 

 (PL XXX. fig. 1.) 



Pedalion mirum . . . Hudson, Mon. Micr. J. vol. vi. 1871, p. 121, pi. xciv. ; and p. 215. 



. . . ,, Qiiart. J. Micr. Sci. vol. xii. 1872, p. 333, pi. xix. 



,, ,, ,, Mon. Micr. J. vol. viii. 1872, p. 209, pi. xxxiii. 



,, Lankester, Quart. J. Micr. Sci. vol. xii. 1872, p. 338. 



SP. CH. Ventral limb much the largest ; dorsal limb on the median line ; lateral 

 limbs in two imequal dissimilar pairs ; the bases of all the limbs, lying in a transverse 

 section dehind the dorsal antenna; their free ends terminating in fans of imbricated 

 seta. 



It was in July 1871 that I had the good fortune to discover this remarkable Eotiferon 

 in a small road-side pond near the head of Nightingale Valley at Clifton. On placing a 

 specimen of it under the microscope I for a moment fancied that I had brought home by 

 mistake some Entomostracous larva, for its outline, its six limbs ending in fans of 

 imbricated set, and its habit of jerking itself through the water, made it resemble the 

 ordinary Nauplius of a Cyclops. However, a brief examination showed it to be a true 

 Eotiferon, with a splendid corona and with internal organs much like those of Triarthra 

 longiseta. The external form is extraordinary ; not only has it six well-developed limbs, 

 but all these limbs are hollow, communicating with the body cavity, and containing pairs of 

 opposing muscles prolonged into their interior. The arrangement of the limbs too is more 

 effective for locomotion than that in a Nauplius ; for in Pedalion they are attached in pairs 

 to its anterior end, and lie parallel to the longitudinal axis of the body, so that their united 

 stroke acts at a great mechanical advantage ; but in the Nauplius larva the limbs radiate 

 from a spot on the ventral surface ; and, in consequence of this inferior method of attach- 

 ment, produce a very feeble skip compared with the furious rush of Pedalion. The 

 corona is unusually large, and consists of two oval saucer-like lobes, so set as to give 

 together a heart-shaped appearance to the head. The ciliary wreath is double, and 

 precisely on the pattern of the Philodinadcs (PI. C, fig. 8). Between the upper and 

 lower wreath is the usual groove along which the food is conducted to the mouth. On 

 either side the lower wreath dips down to the buccal orifice, which is prolonged ventrally 

 into a great curved lip, fringed with very large cilia. The rather small mastax has two 



identical, and that the differences between my description and Dr. Schmarda's " reside principally in 

 the incompleteness of the details given by the latter, and are consequently differences of omission 

 rather than anything else." It is difficult to understand how it can be an " omission " to describe and 

 draw all the six legs as radiating from a spot on the ventral surface, while (on the supposition of the 

 identity of the two creatures) there is only one on that surface, and all lie round the body and parallel 

 to its length. Neither can it well be an " omission " or an " incomplete detail " to say that there are 

 two legs of equal size longer than all the others, when there is only one such leg. Indeed, were Dr. 

 Sci. mar da really capable of the gross blunders attributed to him by Mr. Deby, the whole of his observa- 

 tions would be worthless. 



