302 



ZOOLOGY 



SECT, 



anterior end of the body, above (dorsal to) the mouth and 

 pharynx. On the dorsal surface of the brain, where it comes 

 into contact with the body-wall, is a small red eye -spot (e.). 

 The only other organs which can be considered as sensory are 

 three structures known as tactile rods or feelers ; one of these (d.f.) 

 is a small cylindrical process tipped with stiff hair-like bodies, 

 which -projects from the dorsal surface just behind the trochal disc : 

 the other two (/./.) are paired, situated on the dorsal surface of 

 the lorica and not prominent. 



The tail contains a pair of cement glands (c. gl.) by the secretion 

 of which the animal is able temporarily to attach itself. 



Reproduction and Development. The sexes are lodged 

 in distinct individuals, which present a striking degree of sexual 

 dimorphism. The preceding description applies to the female, 

 which is the form most commonly met with. In addition to the 

 organs already mentioned it has an ovary (ov), connected with a 

 large vitellarium (vt) and opening by an oviduct into the cloaca. 



The male (Fig. 247, A) is a very minute creature, not more than 

 one-fourth the size of the female, and is strangely degenerate in 



c.v 



ov 



do' 



Fi<:. -247. Brachionus rubens. A. male ; B, female, with attached eg^s : <'/'/' nephridial 

 tube ; r. fit. cement glands ; or. ovum in body ; oc.i ova attached to base of tail ; p. penis.,; 

 t. tail ; ts. testis. (After Hudson and Gosse.) 



structure. The enteric canal is absent, the trochal disc simple in 

 structure, the nervous system and nephridial tubes greatly reduced, 

 and the greater part of the body occupied by a large testis (ts.) 

 which opens by a duct at the extremity of a protrusible, dorsally 

 placed penis (p.). 



After extrusion the eggs are attached to the base of the tail 

 of the female (B, ov'.), where they undergo development : they are 

 of- two sizes, the larger giving rise to females, the smaller to- 



