OF WASHINGTON. 27 



Mr. Howard held that the eye-spots of some of the Coccids 

 ought to be called true eyes, and in this was supported by 

 Prof. Riley, who stated that the young all have eyes. 



Prof. Riley further stated that vision must be very feeble in 

 insects such as larvae having eye-spots only, and also called 

 attention to the somewhat remarkable fact of adult insects with 

 highly complex eyes coming from eyeless larvae, as is especially 

 the case in Diptera. 



Prof. Riley presented the following : 



NOTES ON* THE LARVA OF PLATYPSYLLUS. 



BY C. V. RII.KY. 



The discrepancy in size between the larva of Platypsyllus, 

 as hitherto described, and the mature insect, has led me to sus 

 pect that the last larval stage as well as the pupa remained to 

 be discovered. 



A specimen recently obtained and described and figured by 

 me (Eritomologica Americana for February, 1890, pp. 27-30), 

 as the ' ' Ultimate Larva, " is in general appearance strikingly 

 Mallophagous, and a few points may be mentioned as not suf 

 ficiently emphasized in the published description. The ar 

 rangement of setous hairs on the venter recall that in the adult, 

 while the raised dorsal points, though unarmed, foreshadow 

 somewhat the setous points on the dorsal abdominal joints of 

 the adult. Remnants of the anal cerci of the earlier larval 

 stages are noticeable in the two slight swellings on penul 

 timate joint, each surrounded by a series of short spinous hairs. 

 The spiracles are small and lateral, but may be detected with 

 difficulty at the inner angle in the notch between the abdomi 

 nal joints. The prothoracic spiracle has not been detected. 



I have, in the paper alludea to, raised a parenthetical ques 

 tion as to this being the final form of the Platypsyllus larva, 

 but the position and character of the mouth parts, and particu 

 larly the single -jointed tarsi exclude it from the Mallophaga, 

 while its general characteristics, though departing in so many 

 respects from the earlier larva, have caused me to refer it to 

 Platypsyllus a reference which its occurrence on a beaver, in 

 connection with other stages of Platypsyllus and with no other 

 similar insect, strengthens. The principal feature that would 

 shake one's faith in this reference is the presence of ocelli, 

 since none occur in the earlier larva nor in the imago, and 



