98 



Prof. Ehrenberg considers these to be seminal glands ; that some fluid 

 is poured by these into the bladder, and discharged when it is full, 

 I think hardly any one can doubt who watches the operation ; but 

 when we consider that the successive fillings and discharges rarely 

 occupy more than a few minutes, and in many species are performed 

 many times in a minute, though with a very uniform periodicity, — it 

 is hard to think that so great a quantity of fluid can be so quickly 

 secreted. Can it be that the bladder is an organ connected with 

 respiration ? The tortuous vessels carry attached to them, at various 

 points of their extent, little pear-shaped, tremulous organs. They 

 do not always tremble, nor always together, but are very irregular 

 and intermittent ; hence it is difficult to say how many there are, but 

 I have distinctly seen four on each side (H, 3, 3), two near the penul- 

 timate transverse muscle, and two near the neck. When trembling 

 moderately, they are seen to be little oval bags attached to the tor- 

 tuous vessels by a neck, and free at the other end ; a spiral vessel 

 closed at the extremity runs through most of the length, which main- 

 tains a waving motion. When the trembling is rapid, the little bags 

 are dilated at the end (H, 4), and appear as if covered with transverse 

 parallel waves or bands, which run into each other, and disappear 

 successively. In both cases the progress of the waves is from the 

 free extremity towards the neck or base. At the lateral insertions of 

 the antepenultimate transverse muscle a membranous (?) band is 

 fastened to the skin (H, 5), which is attached to the side of the 

 tortuous vessel with a dilated extremity, probably acting as a 

 ligament. 



I have no doubt, with Prof. Ehrenberg, that the little trembling 

 organs are branchiae ; but why should these be attached to the semi- 

 nal glands ? I do not believe, as he does, that water is admitted 

 freely into the visceral cavity ; but may it not permeate the tortuous 

 vessels, be decomposed by the internal (not by the external) surface 

 of the trembling bodies, and then, having performed its office, be 

 poured, effete and waste, into the contractile vesicle, to be dis- 

 charged through the cloaca ? 



Water appears to be constantly percolating into the alimentary 

 canal, even when the jaws are perfectly still ; for there is a succes- 

 sion of little transverse waves continually crossing the neck of this 

 viscus, just below where the duct from the gizzard opens into it. 



Parallel with the gizzard, but nearer the dorsal surface, is a large 

 sub-globose mass of dense matter, white by reflected light, black 

 (because opaque) by transmitted. It occupies the bottom of a deep 



