PUTNAM ON PULVINARIA INNDMERABILIS. 319 



ture 18 esieenUally tbe same, namely: four slender elongated cliitinous setae, with enlarged 

 conical bases, thrust through a davits, and thence through a sheath formed of the lah- 

 ium. In all, the bases are 8upport(>d by a fnime-work something as above described. In fact 

 the only essential variation is in the proportions and minor details of the ditiereut parts. I 

 found it very ea.*y in dissecting the head of a (Jicuda to withdraw the set;e inwards by catch- 

 ing hold of the muscles to which they were attached, with a forceps. All four ser» were in 

 this way easily separated leaving behind the chitinous piece with around hole through which 

 they had been thrust, and which held them in place, being in fact the piece which Dr. Mark 

 has called the clavus. While dissecting the Cicada I noticed that just above and behind the 

 base of the labium on each side ie an external chitinous piece, terminated by a sharp pointed 

 bristle, which appears to be capable of a slight motion, and when separated bears a consider- 

 able resemblance to a mandible. In Psylla I observed the mouth parts of the pupa just be- 

 fore moulting, and of the imago (sex not recorded). In the latter are similar afortive man 

 dibles, rather more distinct than in Cicada, but in the Coccidse I have seen nothing recallinjf 

 these except the small tubercles behind the ventral eyes of the male. In the pupa was no- 

 ticed a new set of setie formed in spirals just as in the Coccidw. It therefore seems reason- 

 able to infer that the setfe of all Homoptera are formed in the same %vay. Taking all these 

 things into consideration I have come, much against my original inclination, to regard there 

 sette as not representative of the mandibles and maxillse as is generally taught. From a note 

 in Dr. Mark's work above referred to (page 6) it seems that Mecznikoff has arrived at a sim- 

 ilar conclusion from a study of the embryos in the eggs of Aspidioius and Aphis. Dr. Henry 

 Shinier has suggested to me that if this is the case, the buccal setae may more truly represent 

 the lingua of oiher insects.] 



The digestive system is almost precisely the same as that of Lccfiniian 

 hesperidum which has been well described by Dr. E. L. Mark.* Begin- 

 ning with the mouth parts above described, a long slender cesophagiis 

 (figs. 26, rt, I; 3")./,- 48, e ; 48,i) extends directly forward from the junction 

 of the buccal setse, then turns upward, passing outside of and around the 

 arciis superior, and backward, extending into the mesothorax where it 

 becomes merged in the chyle stomache {vei)triculus). This becomes en- 

 larged, continues to extend backward a short distance and then turns 

 abruptly forward making three or four convolutions (ansa minor of 

 Mark) inclosed within a sack (apparently the anterior part of the rec- 

 tum / f ). It then forms a very long, ratlier narrow intestine [ansa major) 

 lying free in the abdominal cavity, extending backward nearly as far 

 as the anus, and then forward to near the point of beginning where it 

 joins tiie rectum, thus forming a large loop, and after extending a short 

 distance further terminates in a blind ended sack. The walls of this 

 ventriculus consist of large nucleated cells, very distinctly visible ; these 

 undoubtedly serve to transform the sap absorbed from the tree into pro- 

 toplasmic cells capable of being converted into the tissues. 



A short distance from the beginning of the large loop [ansa major) of 

 the ventriculus it receives the outlet of the so-called malpighian vessels. 

 These are two elongated sacks lying free in the abdomen, one on either 

 side of the rectum, which unite at their anterior ends to form a small 

 short tube which opens into the ventriculus. They consist of large 

 cells filled with a deep yellow granular substance, and in each cell are 

 two (rarely one) large cavities. It seems quite probable that these ves- 

 sels are secretory in their nature, supplying a substance aiding the di- 

 gestion of the food, or its conversion into protoplasm or blood. They 

 may also serve as a means of escape for the waste products of the change 

 of tissues. 



*Beilrage, etc., pp. 20-29. 



