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 Trachea in the Wing of Chrysopa 

 Perla. By J. S. Bowerbank. 



(For the references see Plate XV. J 

 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 Chry- 

 sopa perla, to place it beneath the microscope, that he mio-ht 

 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 



