July 23, 1920] 



SCIENCE 



91 



ceptible and resistant phases, which fact consti- 

 tutes additional evidence that a very intimate re- 

 lation exists between the general physiological con- 

 dition of the egg, and the physical state of its 

 plasma-membrane. During the first ten to fifteen 

 minutes after fertilization the eggs are more sus- 

 ceptible to all substances tried than at any other 

 time until the period just preceding and during 

 the division process. A period of marlced increased 

 susceptibility occurs during the division process 

 which outlasts the furrow formation in most cases 

 about ten to fifteen minutes, and during this inter- 

 val, marlced oytological effects in the eggs are 

 noted. The best records were obtained using i-amyl 

 and capryl alcohols, possibly indicating a higher 

 specific toxicity of these men when compared to the 

 others. 



Notes on the tranches of the aorta {Arcus aortm) 

 and the subclavian artery of the raiiit: Francis 

 Marsh Baldwin. 



Although the usual number of blood vessels aris- 

 ing from the arch of the aorta in the rabbit is two 

 — a so-called innominate or brachio-cephalic artery 

 and a left subclavian artery — the variations from 

 this condition indicate the possibility of a consid- 

 erable departure. In a number of cases, three ves- 

 sels have their origin on the arch and in these the 

 order is the brachio-cephalic, the left common car- 

 otid and the left subclavian arteries. Conspicuous 

 differences in the order and sequence of the vessels 

 from the subclavian arteries of the two sides are 

 noted. On the left side the vessels in a number of 

 cases show a tendency to group themselves either 

 proximally or distally in the form of a sort of 

 corona. 



A study of the phytogeny of certain hymenopter- 

 ous parasites of leaf hoppers: F. A. Fention. 

 This paper deals with the AnteonincB (Dryinidw) , 

 a small parasitic group now classed with the 

 Bethylidce under the Proototrupoidea. "We are now 

 able to trace the evolution of the peculiarly spe- 

 cialized species from the more simple and gener- 

 alized types. So far as our present knowledge is 

 concerned these insects are fparasitie on the leaf- 

 aud tree-hoppers and there is an interesting rela- 

 tionship in the evolution of these parasites with 

 their homopterous hosts. The larvae are mostly 

 externally attached to the host and are incased and 

 protected in the larval exuviae which form a pro- 

 tective sac. The fore tarsi of the adult parasites 

 in a great many oases are modified inta perfect 

 chelse or clasping organs, a fact not found in any 

 other insect group. 



The relative position of the maxima contractions 

 of the Amphiiian muscle when subjected to vari- 

 ous ranges in temperature: Ealph L. Parker. 

 The results of a series of twenty experiments 

 upon the gastrocnemius muscles of frogs showed 

 three apparent maxima contractions within the 

 range of plus ten degrees Centigrade through zero 

 degrees to rigor caloris. These varied to some ex- 

 tent as to what degree the masima fell, depending 

 upon the individual. Rigor caloris of the muscles 

 generally proximated that of the greatest maxima, 

 while that when all were combined and averaged 

 was less than the greatest maxima. Selecting those 

 which recorded in all ranges of temperature and 

 averaging them (seven) the results were nearly 

 parallel to the average of all the muscles and only 

 two maxima contractions appeared. Rigor caloris 

 was greater than the maxiimum contraction. 

 A revision of the Cercopidce of North America 

 north of Mexico : E. D. Ball. 

 The family Cercopidas is the smallest and best 

 known of all the groups of the Homoptera. The 

 writer 's key to the genera and species of the fam- 

 ily published over twenty years ago is now out of 

 date. A number of changes in synonymy and dis- 

 tribution have been made and several species and 

 varieties added and the whole information brought 

 up to date. 



A review of the desert leafhoppers of the Orgerini 



(Rhynchota fulgoridw) : E. D. Ball and Albert 



Hartzell. 



These desert leafhoppers are a group of round, 

 fat, short-winged insects with very peculiar struc- 

 tural modifications probably developed to adapt 

 thean to the extremely hot conditions of the deserts. 

 These modifications consist in an elongation of the 

 rostrum or beak and a lengthening of the legs so 

 that the insect walks upright and its body is thus 

 removed from close contact with the hot sands. 



These insects are all inhabitants of the arid re- 

 gions west of the Rockies and are little known. A 

 number of new genera and species are proposed, 

 together with the classification and life histories 

 of the group. 



Notes on some dipterous parasites of leafhoppers : 



I. L. Ressler. 



Two new species of Pipunculidae, of the genus 

 Pipunculus, reared from the nymph of the leaf- 

 hopper Veltocephalus sayi Pitch are described and 

 discussed in this paper. The PipunculidaB are 

 small flies about one eighth of an inch long, the 

 head being larger than the thorax, and consisting 

 chiefly of the large, closely approximated eyes. 



