198 SUMMARY OF CURRENT RESEARCHES RELATING TO 



ocular emarginations ; it is very broad, more than twice as wide as long ; 

 the temples are large. There is no chitinous plate on the throat, but 

 there is a chitinous framework for the support of the mandibles. The 

 prothorax has its lateral margins rounded. The mesothorax is fused to 

 the metathorax. The pleurites are well-developed. J. A. T. 



Head and Mouth-parts of the Apple-sucker. — A. J. Grove {Para- 

 sitologij, 1919, 11, 456-88, 3 pis., 1 fig.). Description. of Ps?/Z/« ?naU as, 

 regards the exoskeleton of the head (the head-capsule, the buccal region 

 and labium, the setse, and the hypopharynx), the endoskeleton of the 

 head (the tentorium, the salivary pump, and the pharynx), and the 

 complex musculature concerned. In regard to the mechanism of pierc- 

 ing, it is shown that this cannot be due to the ac'-ion of the protractor 

 muscles, and it is suggested that the setse are forced into the host 

 through the agency of the labium, actuated by variations in the internal 

 pressure of the body-fluid contained within it. A raising of the thorax 

 w^hen the labium is in a state of turgescence, and consequently has a 

 firm grip of the setae, will withdraw the setse from the v^ound. As 

 regards the mechanism of sucking, it is suggested that the sap rises in 

 the suction-canal by means of capillarity. The injection of the salivary 

 secretion into the host by the propulsive force exerted by the salivary 

 pump is also discussed. J. A. T. 



Food-canal of Cicada. — 0. W. Hargitt and L. M. Hickernell 

 {Froc. Amer. Soc. Zooh in Ayiat Record, 1920, 17, 351-2). There is a 

 well- differentiated and continuous digestive tube in the adults of both 

 sexes. The alleged discontinuity is not confirmed, but there is a 

 thinning of the digestive epithelium as adult life proceeds. At the 

 posterior end of the relatively short and narrow oesophagus there is a 

 valve which marks the beginning of the crop. Following the crop 

 proper there is an anteriorly directed coil of intestine with Malpighian 

 tubules. The coil lies just dorsal to the crop. Thereafter the intestine 

 run^ dorsally to the seventh abdominal segment where it opens into the 

 rectum. J. A. T. 



Vision in Cicada septendecim.— S. 0. Mast {Froc. Amer. Soc. 

 Zool. in Anat Record, 1920, 17, 345). When the "pupie" emerge 

 from their long sojourn (seventeen years or so) in the ground they 

 make for a tree or the like, which they ascend. If it is dark or if their 

 eyes are covered they no longer go toward the trees. While the trunks 

 of most trees are considerably darker than the rest of the background, 

 those of some trees (e.g. the sycamore) are lighter. But the Cicadas 

 (which appear to be called " locusts ") go toward the latter as well as 

 toward the former. Hence their positive reaction to trees is largely 

 independent of the intensity of the reflected light. They probably 

 perceive the configuration or outline. They almost never climb up on 

 bare buildings. " How the eyes and vision originated in these animals 

 in which they are functional only a few weeks during the seventeen 

 years of their life is an interesting problem." (The origin is surely to 

 be looked for in ancestral forms of different habits.) J. A. T. 



