BOWERBANK ON THE CIRCULATION OF BLOOD. 179 



But it must be observed that, although specimens unquestion- 

 ably British of all these sixty-five insects do exist, yet the 

 majority of the rarer ones, as Daplidice, Lathonia, Antiopa, 

 &c, although exhibited as British, are decidedly and evidently 

 exotic : the three last-named species may be purchased for a 

 mere song. In order that I may not offend gentlemen 

 possessing rich series of the questionable species, I subscribe 

 myself simply, Inqusitor. 



Art. XXII. — Observations on the Circulation of Blood and 

 the Distribution of the Tracheae in the Wing of Chrysopa 

 Perla. By J. S. Bowerbank. 



(For the references see Plate XV.) 

 TO THE EDITOR OF THE ENTOMOLOGICAL MAGAZINE. 



Sir, — You did me the honour of inserting in an early Number 

 of the Entomological Magazine, the result of a series of obser- 

 vations on the circulation of the blood in the larva of Ephemera 

 marginata ; and I regret much that other occupations have 

 prevented me from following up those researches with that 

 degree of attention which so interesting a subject demands. I 

 have, however, occasionally, as opportunities occurred, examined 

 such adult insects as I imagined were likely to enable me to 

 proceed with the subject, and more particularly those whose 

 wings I considered would form favourable subjects for investi- 

 gation, but without arriving at any very satisfactory results 

 until lately. A few evenings since, while strolling with some 

 friends in the cool of the evening, in my garden, I was requested 

 by one of them, who had taken a fine specimen of the Chr?/- 

 sopa perla, to place it beneath the microscope, that he micvht 

 gratify himself by viewing its extremely brilliant eyes. After 

 having pleased ourselves for some time, by examining these 

 beautiful objects, I could not resist the inclination I felt to take 

 a passing glance at the wing, whose transparency, I thought, 

 might enable me to observe some traces of the circulation; and, 

 to my great delight, I saw globules of the blood rushing with 

 rapidity through the two large canals of the under wing. As, 

 however, I had unfortunately grasped the thorax of the insect 

 with the forceps, life very shortly became extinct, and with it 



