338 



SCIENCE. 



[Vol. II., No. 31. 



Professor Riley thought that this class of observa- 

 tions could apply only to certain localities, and that in 

 the southern states the conditions might be entirely 

 changed. Professor Forbes thought there were three 

 distinct broods per year in Illinois. As late as July 

 he had found eggs of a brood already abroad. 



The structure of the skull in Diclonius mira- 

 bilis, a Laramie flinosaurian. 



BY E. D. COPE OP PHILADELPHIA, PENN. 



A BLACKBOAKD sketch of this dinosaur, as recon- 

 structed by Professor Cope, attracted much attention. 

 The animal existed in the mesozoic age, and is esti- 

 mated to have been 38 feet long. The skull, which 

 is about four feet in length, is in profile a good deal 

 like that of a goose, but, seen from above, is some- 

 what like that of a spoonbill. Skulls of this type of 

 reptiles are rarely found, and this one throws much 

 light on the question of the classification of the order. 

 The arrangement of the teeth is very peculiar; and 

 the number is very great, amounting to nearly 2,000. 

 The general form of the animal is that of a gigantic 

 kangaroo. The food evidently consisted of very soft 

 aquatic vegetation. 



The trituberculate type of superior molar, and 

 the origin of the quadrituberculate. 



BY E. D. COPE OF PHILADELPHIA, PENN. 



In the lower eocene. Professor Cope finds all the 

 mammalian molar-teeth to be trituberculate. He 

 has now a complete series of molar-teeth from differ- 

 ent mammals in successive horizoiis, showing all the 

 steps of transition from trituberculate molars of 

 somewhat triangular form and very simple structure, 

 up to the regular quadrituberculate tooth, which is 

 defined as of nearly square section and having four 

 tubercles. Man has quadrituberculate molars : all 

 the monkeys are similarly equipped. Some of the 

 lemurs have trituberculate teeth. Among lower 

 types, such as marsupials and hedgehogs, about half 

 have the tri- and half the quadri-tuberculate develop- 

 ment. The insectivora are similarly divided, about 

 half having the old eocene molars and half the 

 modern form. The various steps of development 

 were illustrated by blackboard-drawings. 



Two primitive types of Ungulata. 



BY E. D. COPE OF PHILADELPHIA, PENN. 



The author announced the discovery of a new 

 mammalian fauna of the eocene, having the follow- 

 ing characteristics : 1°. All the fingers and toes are 

 retained; they are plantigrade, each limb having five 

 digital extremities. 2°. The limbs are shorter than 

 usual. 3°. They invariably have a flat astragalus. 

 To the second specification there is one exception, a 

 swimming animal whose hind-limbs were long. One 

 of the discoveries is of a hoof-type animal with 

 carnivorous jaws. It existed in the eocene, and 

 appears to have been of short duration. 



In the discussion on this paper, Dr. Dawson stated 

 that some of the plants he had traced in the eocene 



were well adapted, by the circumstances under whicli 

 they grew, for supplying food to the creatures de- 

 scribed. Professor Cope received this announce- 

 ment with expressions of pleasure. Thus the new 

 mammal of the old eocene not only bridged the 

 interval between ungulates and carnivores, but also 

 the wider gulf between Dr. Dawson and Professor 

 Cope. 



Pharyngeal respiration in the soft-shelled tur- 

 tle, Aspidouectes spinifer. 



BY S. H. GAGE OF ITHACA, N.Y. 



During the last twenty-five years, respiration in 

 the Chelonia has been investigated with considerable 

 thoroughness, both in this country and in Europe; 

 and at present the chelonian form of respiration is 

 considered to be comparable witli that of the mam- 

 mal, rather than with that of the frog as formerly sup- 

 posed. While, however, the mechanism of respira- 

 tion has been very fully investigated, there has been, 

 so far as the author is aware, but one investigator 

 who has considered the organs of respiration in the 

 different groups of turtles. The author showed rea- 

 sons for believing that a true aquatic respiration, and 

 a true aerial respiration, co-exisled in the soft-shelled 

 turtle. It is hoped, that, during the coming year, 

 investigations may be completed which shall deter- 

 mine the exact proportion of the pharyngeal i-espira- 

 tion, and the structure of this unusual respiratory 

 organ. 



The application of nitrous oxide and air 

 to produce anaesthesia; with clinics on 

 animals in an experimental air-chamber. 



BY B. P. HOWLAND OF WASHINGTON, D.C. 



The paper opened with the conclusion of the 

 author that a mixture of nitrous oxide and oxygen, 

 administered in a clused air-chamber, would event- 

 ually take the place of ether and chloroform as an 

 anaesthetic for all surgical operations. As ordinarily 

 administered, nitrous oxide cannot be used for pro- 

 longed operations, because the blood does not separate 

 oxygen fi'om the gas. ISTitrous oxide is expelled from 

 the lungs without change: if it is supplied to them 

 without air or oxygen, death ensues from asphyxia. 

 The author claimed to have administered nitrous 

 oxide for dental and surgical operations in over 30,000 

 cases. He has found that where unmixed nitrous 

 oxide is used, in the average of cases insensibility is 

 produced in fifty seconds, and recovery from uncon- 

 sciousness takes place in two minutes. With animals 

 experimented upon, in the average of cases, death 

 ensued within two and a half minutes, where air or 

 oxygen was excluded. 



If, at the ordinary pressure of the atmosphere, 

 enough air is mixed with nitrous oxide to support 

 respiration, the mixture fails in producing anaesthe- 

 sia. But the increase of pressure which can be 

 eiiected by administration in an aii-tight chamber 

 changes tlie result materially. In such a chamber, 

 with suitable air-pressure, equal parts of air and 

 nitrous oxide breathed from a gas-bag, or a mixture 



