NATURAL HISTORY SOCIETY OF GLASGOW. 59 



curious process projects, beneath which is the common anal and 

 genital orifice, and close to this process the nervous ganglion is 

 situated. At the bottom of the branchial sac lies the mouth, 

 stomach, and intestines, heart, and large vessels. The rectum 

 passes up along one side of this sac to the orifice. Beneath the 

 process, and in close proximity to it, one or two ova in an advanced 

 stage of development may be frequently observed. The caudal 

 portion of the animal contains the reproductive organs. In what 

 part the ova are fertilized is not easily made out, but there could 

 be no doubt of the presence of sperm cells. The more advanced 

 ova contained the curious little tadpole-larvae, ready to be extruded. 

 They are of an orange-red colour; a dark triangular patch repre- 

 sents the stomach, and the tail is curved, on one side of the ovum, 

 towards the head. Eound this front portion of the larva is a 

 semicircle of cells, mth three button-shaped processes on the sur- 

 face next to the outer membrane of the ovum, which are con- 

 nected, in some examples, by processes extending towards the 

 centre of the semicircle of cells. By these button-shaped pro- 

 cesses the larva, after passing some time swimming about in the 

 free state, is said to settle down on a shell, stone, or some other 

 object, where, like its parent, it adheres firmly for life. Some of 

 the ova are of a dark brown, with a white nucleus ; others again 

 are of a yellowish tint, witli granules in the centre of an orange 

 hue. A progressive development is observed in each as they 

 ascend from the lower portion towards the common orifice. 



In one or two of these animals what appeared to be an ovum 

 was filled with a number of little ovules, in each of which was 

 a bright red dot; or, in other words, in the same situation, and 

 beside the other ova which contained the tadpole-larvae, there was 

 a cyst or sac of precisely similar size and form, filled with these 

 red-dotted ovules; and in another animal we found the same cyst, 

 with the ovules not so far advanced, and wanting the red spot. 

 On slight pressure the sac gave way, and these o^^.lles were dis- 

 charged. Each of them was then found to present a red eye-speck, 

 like an entomostracan, and there appeared to be a stomach-mass 

 filled with reddish-yellow granules. When the envelope of the 

 owile iDurst, the limbs wliich had been previously pressed close to 

 the side of the body were expanded ; three pair were observed to 

 be given off" from the upper half of the body; of the first pair, each 

 was terminated by two setse; the number of articulations, how- 



