OF WASHINGTON. 305 



The first half hour was devoted to a discussion of Dr. Gill's 

 paper presented at the last meeting. Dr. Gill stated the main 

 features of his paper, after which it was discussed by Messrs. 

 Stiles, Smith, Riley, Gill, Banks, and Ashmead. 



Dr. Riley then read the following papers : 



ON CERTAIN PECULIAR STRUCTURES OF LEPIDOPTERA. 



BY C. V. RILEY. 



i. THE RADIATE BODIES IN THE RECEPTACULUM SEMINIS OF 

 PRONUBA AND PRODOXUS. 



In preparing a resume of the facts connected with Yucca polli 

 nation for the Annual Report of the Missouri Botanical Garden, I 

 had occasion lately to characterize definitely the undescribed 

 species of Pronuba and Prodoxus, and in connection with the 

 descriptions presented herewith for publication I would call atten 

 tion to some of the peculiar structures of these remarkable insects. 

 Pronuba synthetica pollinizes Yucca brevifolia* and is a rather 

 anomalous Lepidopteron, bearing a striking superficial resem 

 blance to certain saw-flies of the genus Dolerus, as also to certain 

 Neuropterous species of the family SialidaB. Aside from the curi 

 ous maxillary tentacles and serrate ovipositor of the female, pecu 

 liar to the genus, the body is flattened and the scales of the wings 

 so loosely attached and so sparse that they disappear as readily as 

 in the case of the Sesiida3, and are seen in perfection only in the 

 recently emerged individuals. But it is not the external peculiar 

 ities of this insect to which I wish to draw attention in this note 

 so much as the peculiar radiate bodies in the receptaculum sem- 

 inis, which, if they occur at all in other insects, are never found 

 in anything like the remarkable development in which they exist 

 in the species of the family Prodoxidse. In the very first studies 

 of Pronuba yuccasella these radiate bodies were noticeable, and 

 have been referred to by me as being visible even through the 

 sides of the body when this is rendered in any way transparent. 

 They consist of a pair of brown, chitinous radiate structures, each 

 with a darker central circular ring or hub. More closely studied 

 this circular ring is seen to represent the end of a hollow though 

 shallow cylinder, from the sides of which the spicules radiate. 

 The individual spicules have an inner groove or channel running 

 from the very tip to the base. I present some drawings which 

 will indicate the relative size of the pear-shaped receptaculum in 

 the three known species of Pronuba and in Prodoxus decipiens ; 

 also the relative dimensions of the radiate bodies. It will be seen 

 that they are very much the largest in Pronuba yuccasella. In 

 Pronuba synthetica they are next in size ; in maculata next ; 



