OF THE HYDATIX^A. 



601 



view of this animalcule extended, with 

 six colourless eyes in each gi-oup ; 428, a 

 specimen with foui' eyes ; 429, body con- 

 tracted, but jaws extended.) Amongst 

 Oscillatoriae. 1-140". 



T. uncinatus. — Toes long, a frontal 

 uncinus, or hook, present. Six visual 

 points have been seen by Ehrenberg. 

 Amono-st Oscillatorise. 1-240" 



The two next genera mentioned are from Mr. Gosse, who, however, adduces 

 the latter one as a doubtful member of the present family. 



Genus ASPLAXCHNA (Gosse, A. N. H. 1850, vol. vi.) (XII. Q^, 66 ; 

 XXXVI. 7-9 ; XXXYII. 27-32).— Eotatorial Hydatin^a destitute of foot, 

 intestine and anus, but possessing eyes (ocelli) and jaws ; sexes disjoined. 



This new genus embraces the Eotatorial animal which Mr. Brightwell 

 introduced to notice as '' a supposed new species of Notommata " {Fauna 

 Infv^oria, Norfolk, 1849), and in which he first detected the existence 

 of male animals distinct in organization and character from the female. 

 It was soon perceived that the new forms represented by Mi\ Bright- 

 well could not belong to the genus Notommata of Ehrenberg; and the 

 discovery of other similar beings has led to the creation of this genus 

 Asplanclma, 



AsPLAXCHXA Brightwellu. — Jaws 

 (mandibles) one-toothed ; eye single ; 

 stomach oval, longitudinal ; vesicle lobed, 

 larger; tremidous corpuscles (gills, Ehr.) 

 affixed to a long filament; ovary two- 

 horned. Length about 1-24". (xii. 65. 

 66.) Males with jaws, pharjTix, and 

 stomach absent ; body truncate. Length 

 about 1-40". Found at Norwich, Lea- 

 mington, Hampstead Heath, &c. 



Mr. BrightweU's account is embraced 

 in the following extracts : — 



" It (the female) is furnished witli an 

 ovisac, in which the young may be clearly 

 detected, and from which they are ex- 

 pelled through the sides of the animal. 

 Some of the yoimg appear to differ in 

 fonn from the others, and there appear 

 to be two kinds of ova, — one, and that 

 by far the greater nimiber, transparent, 

 and hatched in the body of the parent ; 

 the other, more opaque, perhaps remain- 

 ing unliatched, or deposited till vivified 

 under favourable circumstances in some 

 ensuing season. Should this, on fm-ther 

 investigation, tm'n out to be the case, 

 we shall have, amono- the Rotifera, the 



repeatedly seen the male in connexion 

 with the female. He attaches himself 

 to her side by his spenn-tube, and re- 

 mains attached from twenty to seventy 

 seconds." 



For a more complete description of 

 these very interesting forms we may 

 refer the reader to the elaborate details 

 and figures of their organization, by Mr. 

 Dalrymple, in the Pliilosophical frans- 

 actions for 1849, and to Part I. p. 453 

 et seq. of this volume. 



Notommata Anglica of Leydig appears 

 to be only Mr. Gosse's Asplanchna Bright- 

 icelUi. 



A. priodonta (Gosse). — Females : Jaws 

 serrated ; eyes three ; stomach hemi- 

 spherical, transverse ; vesicle spherical, 

 smaller ; tremulous bodies attached to a 

 twisted and plicate filament ; ovary sub- 

 globose (xxxvi. 9 ; xxxviii. 28). Leng-th 

 about 1-48". Males : Body acute (xxxvi. 

 7, 8). 1-110". Found in the Seroentine 

 river. (Figs. 10, 11 exhibit the jaws of 

 the female detaclied.) 



A. SieboIdn(Nofommafa Sieboldii, Ley- 

 dig) (xxxvn. 27-^2). — Females closely 

 resemble those of Leydig's N. Anglica^ 

 but the males differ widely. Female 

 campanulate, no foot ; anterior exti'e- 

 mitv widened ; ciliarv ^vreath inter- 



same mode of preser^-ing the ova during 

 the winter as is found in some of the 

 Entomostraca, the Daphnice for instance." 



'' These [the males] are smaller than , ^ 

 the females, and have a pp-iform sac ■ rupted by a fissure at the mouth, into 

 below, from which there is an opening, | which the fine cilia descend ; two large 

 and which is filled with spermatozoa ; j lobes (32 g) on the rotary organ, crowded 

 and they have neither jaws, nor gullet, \ by setse, wdth two similar smaller ones ; 



nor stomach ; and it would seem they 

 are designed, as is the case with the 

 males of some insects, to continue the 

 race and then to perish .... I have lately 



between these, on each side, is a fossa 

 with long motionless setae. Mouth open- 

 ing into an angular maxillary bulb. 

 Jaws (xxxYii. 31) with one furcate piece 

 2t2 



