SCIENCE. 



[N. S. Vol. XIV. No. 348. 



two species. Perhaps the mottled, ox- more 

 properly the streaked, appearance of the larvae 

 of punctipennis is a distinguishiug feature. 

 Dr. Howard, we believe, mentions nothing of 

 the kind in regard to maculipennis. 



The duration of the larval stage, under nor- 

 mal conditions with plenty of food, varied from 

 twelve to fourteen days. 



On June 5 three larvse were placed in a 

 jar containing very little food. What food 

 there was lay among some sand at the bottom. 

 Two of them were very young, vrhile the third 

 could not have been more than half grown. 

 These larvae I'emained there until June 29, 

 when the two younger died. These two did 

 not go to the bottom after food and x^robably 

 starved. The third and more mature one did 

 go to the bottom after food and remained alive 

 until July 3, when it was transferred to 

 water containing an abundance of food. In a 

 few days it transformed to a pupa. In this 

 case the larval stage was over a month and 

 could doubtless have been prolonged. 



Pupas. — The pupse of Anopheles are not 

 strikingly different from those of Culex pipiens 

 to the unaided eye. A close observer, however, 

 can learn to distinguish the two with the eye 

 by the diiFerence in length of the respiratory 

 siphons. Those of J nop/ie/es are much shorter. 

 Under the microscope they are also seen to be 

 of quite a different shape from those of Culex. 

 The thorax and, body of A. punctipennis diflPer 

 quite markedly in shape from those of C. pip- 

 iens, when seen from above. Like the larvae, 

 the pupse tend to wriggle in a horizontal di- 

 rection when disturbed. They are not as active 

 as those of C, pipiens, which fact is brought out 

 very forcibly when one attempts to make a 

 camera lucida drawing of the living pupse of 

 both in their natural position in the water. 



The pupal stage of both males and females 

 lasted with great regularity just about two days. 

 At least it could not have varied more than a 

 few hours from this, as the adults were found in 

 every case on the second morning subsequent 

 to the morning on which the pupse were 

 found. 



Egg-laying of Calex Pijiiens. — On July 17, in 

 the back yard of a hotel at Magnolia, Missis- 

 sippi, the writer found a pig trough five feet long, 



containing water to the depth of about six inches. 

 On the surface of this water hy actual count 

 there were 257 masses of eggs of C. pipiens. Since 

 there were less than five square feet of surface, 

 one can imagine the density of egg population. 

 'It was noticed that about a dozen of the egg 

 masses were white, or yellowish white, in ap- 

 pearance. This led to a more careful examina- 

 tion, which resulted in the discovery of a female 

 about to finish laying a batch of eggs. Time, 6 

 a.m. She was so busily engaged that we could 

 watch her with a hand lens. She rested on the 

 surface with the abdomen at a slight angle, be- 

 cause the caudal end was nearly touching the 

 surface. The mosquito stood at one end of the 

 mass, with her head away from it. As the eggs 

 were deposited the mass was gradually pushed 

 away from her. The end of the abdomen was 

 slowly carried from side to side, so that the eggs 

 might be placed across the end and the whole 

 mass filled out and completed as she progressed. 

 The process may be compared with the action of 

 the hand as a bobbin is wound with thread. The 

 eggs always came forth with the small end first. 

 This end, since the abdomen was held closely 

 to the mass, would strike the other eggs and 

 appear to be slipped along the perpendicular 

 sides of the others, and thus be brought to an 

 upright position. However, the tip of the ab- 

 domen was curled slightly upward, so that the 

 egg was directed upward and vei'y likely would 

 have been deposited in an upright position in any 

 case. It would have been interesting to have 

 seen the first egg deposited. There was an ap- 

 preciable interval between the deposition of 

 each egg, iDerhaj^s two seconds, although we 

 did not time it. 



Glenn W. Hereick. 

 Agricultural College, Mississippi. 



RECENT ZOO-PALEONTOLOGY. 

 A MARSUPIAL EVOLUTION. 



In the April Naturalist * is an important paper 

 by Mr. B. Arthur Bensley upon the origin of 

 the Australian Marsupialia. The evolution of 

 the Marsupials is compared with that of the Pla- 



* ' A Theory of the Origin and Evolution of the 

 Australian Marsupialia,' The American Naturalist, 

 Vol. XXXV., No. 492, pp. 245-269, April, 1901. 



