INDUSTRIAL PROGRESS DURING THE YEAR 187G. cli 



INVERTEBRATE ZOOLOGY. 



By Dr. A. S. PACKARD, Jr. 



The Rhizopods of this country are still undergoing examination 

 by Professor Leidy. In sj3eaking of the Difflugian Rhizopods, Dr. 

 Wallich expresses the opinion that the whole are referable to a 

 single specific type, while Dr. Carpenter is quoted as saying that 

 " whether it will ever be practicable to arrange the multitudinous 

 forms of this group in natural assemblages, whose boundaries shall 

 be capable of strict limitation, is to us by no means certain." Dr. 

 Leidy adds that it would seem that the existing rhizopods, in re- 

 spect to classification, may be viewed as an epitome of all organic 

 forms in all times ; for, if all these could be known, it would be 

 found that there were no absolute limits defining species, or any 

 other of the usual divisions in classification. Many of the fresh- 

 water forms of this country are identical with those of Europe, The 

 Amoeba, it will be remembered, is the simplest form of rhizoiDod, 

 while the shelled forms are called Foraminifera, and Eozoon is sup- 

 posed to be one of these. 



An account by Hertwig of a new acinetan infusorian {PodojjJiri/a 

 gemmipara) appears in the new German Journal of Anatomy and Em- 

 hryology, edited by Gegenbaur. After a review of the structure of 

 the Acinetae generally, the author speculates on the origin of these 

 interesting forms, and believes that the original ancestral form from 

 which the Acinetse and infusoria sprang was a one-celled organism 

 covered with cilia. 



Dr. Biitschli describes the production in Podoplirya of ciliated 

 young, somewhat resembling those of other normal Infusoria 

 ciliata. 



The sun-animalcule {ActinojyJirys Sol) has been observed by Mr. 

 Fullagar to pass through the following changes. After encysting, 

 having previously drawn in its spine-like " pseudopodia," it divides 

 into two equal-sized globes, which, after remaining separate for a 

 few hours, unite again, forming a smaller sphere than the original 

 one. It now moves about by thrusting out two or three pseudo- 

 podia, and then resting for a while. At times also a cloudy matter 

 exudes from them, out of which Amoeba-like bodies proceed, re- 

 sembling the forms of difterent so-called species of Amoiba. The 

 author asks, " What connection have they with Actinophrys Sol, be- 

 ing found so closely mixed up with them ?" He does not answer 

 the question ; but, judging from the mode of development of certain 



