530 Linncean Society. 



that of any other known species of Tenthredinidce ; the caterpillars 

 of the solitary saw-flies, especially the larger species, forming single 

 oval cocoons of a very tough and leathery material attached to 

 twigs ; and those even of the gregarious sjDecies placing their co- 

 coons (which are oval cases of silk and gum) in an irregular manner 

 with no unity of design. The caterpillars of Dielocerus ElUsii, on 

 the contrary, which are evidently gregarious, unite to form on the 

 branch of a tree, an oval or elliptical case, four or five inches long, 

 narrowed superiorly, very uneven on its surface, and of a dirty 

 whitish ochre in colour. The cells, thirty-eight in number in the 

 nest examined, are placed at right angles to the branch, piled hori- 

 zontally one above the other, unequal in size and irregular in form, 

 those next the tree being pentagonal, the central ones hexagonal, 

 and some of the outer ones nearly round or oval. In one of these 

 cells Mr. Curtis found a dead female, and most of them had the 

 exuviae of the caterpillars remaining, but no shroud of the pupae ; 

 he thinks the smaller cells may have been occupied by the males. 

 At the end of each cell is a circular lid, formed of the same leather}'' 

 material as the rest of the comb, which being cut round by means of 

 the sharp mandibles, leaves an opening through which the saw-flies 

 make their way. In two of the cells were found the dead cater- 

 pillars, which closely resemble those of the genus Hylotoma. 



The author observes upon the dissimilarity of the mode of forma- 

 tion of this nest to that of any previously observed, the compound 

 nidus (as far as hitherto known) being always the work of the parent 

 insects for the protection of their young through the first three stages 

 of their existence. In this case, however, it is formed by the larvae 

 themselves for the purpose of their own metamorphosis. The nearest 

 approach to this economy seems to be the nidus formed by the mag- 

 gots of some of the Iclmeumones adsciti, whose silken cells are placed 

 regularly in rows. 



Mr. Curtis then proceeds to describe two species of Schizocerus 

 from his own cabinet with the following characters : 



S. nasicornis, <? niger, abdomine pallid^ ochraceo apice nigro, alls nebu- 

 losis, pedibus fuscis; femoribus 4 posterioribiis ochraceis, capite antice 

 1-dentato. 



S. ochrostigma, S fusco-niger, alis obscure hyalinis : costa stigmateque 

 flavis, pedibus ochraceis ; tibiis tarsisque posticis fuscis. 



The other nest brought home by Mr. Ellis is that of a wasp of the 

 Fabrician genus Polistes, but differing apparently from any of the 

 species hitherto recorded as forming similar habitations. The insect 

 by which it is constructed is thus characterized : 



Myraptera hrunnea, sericeo-fiisca, pedibus ochraceis, femoribus genubus 

 tibiisque 4 posterioribus (nisi basi) fuscis, maculis duabus in genis 

 flavis. 



The nest is attached to a twig not much more than an eighth of 

 an inch in diameter. It is eight inches long and fifteen in circum- 

 ference, pear-shaped, and having on its outer margin a hemispherical 

 tubercle pierced with a circular hole a little more than half an inch 



