OF THE BRACHIOXJiA. 



ro9 



individual example, vesemhlesA.foliacea, I the peculiar upturned tooth iu the median 

 but is less flat, more cubical, and possesses | line, (xxxviii. (5.) 



Genus BRACHIOiS'US. — Brachionsca which have a single cervical eye and 

 a furcate foot. Figure compressed. Lorica closed at the sides ; open at the 

 extremities like a tortoise-shell. Anterior and posterior margins usually 

 dentate ; sm^face either smooth or rough and tuberculated, the tubercles on 

 the abdominal surface arranged in four lines diverging posteriorly. The 

 cuticle, which, according to Leydig, rests on a molecular layer, resists 

 Uquor potassse. The frontal processes or teeth are dentate on their inner 

 edge. Animal able to withdraAV itself within the lorica. Rotary organ 

 simple, and, though often looking as if lobed, presenting an unbroken border, 

 except when it is indented by descending to the mouth, whence this bilobed 

 aspect ; a median lobe and two lateral ones arise from its free surface. On 

 its right and left side are some eminences surmounted by long bristles, in 

 addition to a long bristle projecting backwards from each lateral margin of 

 the rotary organ. A granular mass, the supposed cerebral ganglion, supports 

 the eye-speck, which is extended backwards into two points. A siphon, or 

 tactile tube, tenninated by a bunch of setse, projects from between the an- 

 terior median teeth of the lorica. Two brown vesicles in front of the large 

 muscular oesophageal bulb, in which are the toothed jaws ; a short oesopha- 

 gus ; and a stomach, the latter composed of coloured cells, ciliated on their 

 free surface. In front of the stomach two pedunculate glands. Intestine 

 clear and ciliated. Contractile vesicle on the right of the cloaca, with two 

 water-vascular canals proceeding from it to the neck, where they form a 

 plexus and bear two tags. Ovary beneath the stomach. Eggs, according to 

 Perty, of three sorts, viz. winter ova, summer ova, and ova bearing male 

 embryos. Ova attached to the exterior of the animal. B. Pala, B. urceolaris, 

 and B. ruhens sometimes increase in such quantities as to render the water 

 milky and turbid. Several species are infested with VorticeUa, Ejjistylis, 

 and other parasites, which attach themselves to their sheUs. Like Asplanchna, 

 EucJilanis, and others, the genus Brachionus has acquii^ed great additional 

 interest from the discovery amongst some of its species of the distinct sepa- 

 paration of the sexes. The male Brachioni present a different form to that 

 of the female, resembling, in this respect, AsjpIancJina Sieboldii rather than 

 A. Brlghtwellii and Hydatina senta, in which the difference of external con- 

 tours is mainly one of size. The multiplying discoveries of separate sexes 

 amongst the Rotifera, combined with the manifest absence of male organs 

 in the numerous individuals provided with ovaries, renders it increasingly 

 probable that all the Rotifera will finally be demonstrated to be bisexual or 

 dioeceous. 



Brachionus Pala. — Lorica smooth, 

 with four spines in front, and two obtuse 

 ones near the opening for the foot. Toes 

 of the foot apparently bifid. This crea- 

 ture swims m a perpendicular position, 

 the brow being directed upwards. Each 

 jaw has five teeth ; the alimentary canal 

 being constricted, forms a stomach. 

 Length 1-36" ; lorica only 1-48" (xxxix. 

 14,15). :i y 



B. amphiceros. — Has a smooth lorica, 

 with four spines, in front and poste- 

 riorly ; four sharp posterior teeth are 

 characteristic. 1-72". 



B. w'ceolans (Brachiorms urceolarts, 

 M.). — Whitish ; lorica smooth, with six 

 very short spines in front ; posterior ex- 

 tremity rounded ; lorica slightly granu- 

 lated ; its points are shorter and less 

 sharp than in the following species ; 

 delicate longitudinal ridges proceed from 

 the spines ; the jaws have each five 

 teeth. 



The males of Brachionus urceolaris, 

 according to Perty, are developed from 

 smaller ova than the females, these eggs 

 being also adherent to the parent in 

 greater numbers. They are very splie- 



