PSYCHE. 



THE PRIMITIVE NUMBER OF MALPIGHIAN VESSELS IN 



INSECTS.— IV. 



BY WILLIAM MORTON WHEELER, PH.D., CHICAGO, ILL. 



Ephemeridea. Schindler* estimates 

 the number of Malpighian vessels of 

 Ephemeridea vulgata at about 40. I 

 have examined the nymphs of three 

 species of Ephemeridea belonging to 

 the genera Blasturus and Ecdyurus. In 

 one the vessels open separately into 

 the gut ; while in the two others they 

 are distinctly ramified. An older 

 nymph of one of these species had 

 about 12 primary trunks, whereas in 

 two much younger specimens there 

 were only S. In all three species the 

 vessels were coiled and much enlarged 

 at their tips, so that the whole mass 

 resembled a chevaux-de-frise. Schind- 

 ler found similar conditions in Ephe- 

 mera Jlavipes. I believe that the eight 

 primary trunks in the young Ephemerid 

 represent in great part primitive ves- 

 sels. The still younger larva or the 

 embryo probably has only 4 or 6 simple 

 diverticula of the hind-gut. 



Odoxata. Nothing is known con- 

 cerning the embryonic Malpighian 

 vessels in this order. Schindler f found 



* 1. c. p. 623. 

 t I. c. p. 626. 



50-60 vessels in imagines of Libellula 

 Jlaveola, L. depressa, Aeschna gran- 

 dis, Calopteryx splendens and Agrion 

 puella. It is more than probable that 

 the larvae and embryos have a much 

 smaller number. 



Plecoptera. Perla bicandata ac- 

 cording to Schindler * has 50-60 vessels. 

 I have been unable to secure embryos 

 of this interesting order. It is certain, 

 however, that the larvae must hatch 

 with very few vessels, since a 5 mm. 

 black and yellow Perlid larva, not un- 

 common under stones in rapid brooks 

 near Worcester, Mass., had only 14 

 vessels. The nearly mature nymph of 

 the same species (16 mm. long) had 

 more than 50. 



Corrodextia. Lespesf found S 

 Malpighian vessels in Termcs lucifu- 

 giis. Fritz Midler \ found 6 or 8 in 

 Calotermes and u bei vielen arten von 

 Termes und ebenso bei Eutermes unci 



* 1. c. p. 625. 



t Recherches sur reorganisation et les moeurs du 

 Termite lucifuge. Ann. sci. natur. 4. ser. zool. v. 

 1856. 



I Beitrage zur kenntniss der Termiten. Jen. zeitschr* 

 bd. ix, iS75. 



