400 Anyials Entomological Society of America [Vol. IX, 



stems in the alder flea beetle is probably homologous with this 

 fusion into two pairs in Donacia. In Haltica, these vessels 

 enter the colon wall and terminate blindly there, whereas in 

 Donacia, they are fused into two pairs which lie free in the body 

 cavit}^ throughout their extent, and they have no free distal 

 ending. 



The vessels of the second series also present a very marked 

 contrast in the two forms, the only point of similarity being 

 that in both species they are shorter than the first series, and 

 have isolated insertions. But whereas they are slender and 

 delicate in Haltica, they are large and swollen in Donacia, 

 much larger than the tubes of the first series, a very unusual 

 condition which has been reported for no other chrysomelid 

 genus. The distal ends of the vessels lie in the wall of the colon 

 Haltica, and free in the body cavity in Donacia. 



In Crioceris the conditions are almost identical with the 

 alder flea beetle, in so far as Dufour has described them. In 

 Cassida, the ventricular insertion is very different, but the 

 superficial distal insertion is very suggestive of the condition 

 in H. bimargi?iata. 



Although Dufour was the first to state the probability that 

 the posterior insertion of the vessels is merely superficial in all 

 cases, he does not appear to have been fully convinced that this 

 was true, especially in Myrmeleon formicarium. It remained 

 for Sirodot in 1858, who summarized the results of earlier workers 

 in a very satisfactory way, to demonstrate that in all cases, 

 not excepting Myrmeleon, the posterior insertion is absolutely 

 superficial, the vessels simply ramifying in the wall of the 

 canal. His final statement in regard to the matter was: "As 

 a general conclusion, then, the extremities of the Malpighian 

 tubes are either free or united in bundles, but always without 

 any alteration of the independence of their lumen. " (Page 261). 



Schindler's paper in 1878 was the next important contribu- 

 tion to our knowledge of the Malpighian vessels. Summarizing 

 the results of his own studies on Coleoptera and those of 

 preceding writers, he said: "Where one finds six vessels, it is 

 often the case that they unite with one another at their extrem- 

 ities into one or two apparently common stalks, and seem to 

 empty into the rectum, which is however, never the case, for 

 after the common stalk has penetrated the outer layer of the 



