334 Analysis of Scientific Books. 



mologists will be surprised at, and perhaps disinclined to listen to, 

 the opinion here advanced with respect to a sanguineous circula- 

 tion in insects ; but I nevertheless hope that the opinion will not 

 be rejected without some previous attention to it. With regard to 

 the dorsal vessel of the gryllotalpa, which in this, as in other in- 

 sects, has been supposed to stand in the place of an arterial heart, 

 I have very few observations to offer. It does not agree in form 

 with the description commonly given of this mysterious organ; 

 for though it diminishes in diameter as it approaches its head, this 

 is by no means the case towards the other extremity of it. I have 

 not yet completely succeeded in tracing this vessel to the anterior 

 extremity ; because as it approaches its termination in that direc- 

 tion, it becomes so delicate as to have hitherto broken under dis- 

 section before I arrived at the extremity of it. Towards the op- 

 posite extremity it gradually becomes larger from the centre of 

 the body, and terminates apparently in a cul-de-sac about the 

 last segment but two of the abdomen." 



The dimensions of a full-grown mole-cricket are as follow: — 

 Length of the body, from the extremity of the lip Inches , 



to the extremity of the vent . . . 2.0 



Length of the head ... . 0.165 



Length of the thoracic division . . 0.5 



Length of the abdominal division . . 1.33 



Breadth of the thorax . . . 0.5 



Breadth of the abdomen - . .0.5 



Length of the antennae of the head . . 0.825 



Length of the caudal antennae . . 0.666 



Length of the whole alimentary canal . . 2.0 

 Length of the oesophagus . . ; 0.5 



Length from the crop to the great intestine . 0.5 

 Length of the great intestine . . 1.0 



We cannot take leave of Dr. Kidd without congratulating him 

 on the perspicuous method of arrangement and description which 

 he has pursued in this paper, and trust that he will continue to 

 labour in a field of inquiry abundant in materials, and much in 

 need of that elaborate, unaffected, and unprejudiced spirit of pur- 

 suit in which he has entered it. 



ii. Further Observations on Planarice. By J. R. Johnson, M.D., 



F.R.S. 



Some account of Dr. Johnson's former observations upon these 

 singular insects, will be found in the fourteenth volume of this 

 Journal *. In the present communication, he adds another singular 



* Pa&e S87. 



