June 19, 19 



SCIENCE 



953 



Northwest Pacific Ocean, some new Dajidse 

 were collected, one being the type of a new 

 genus, Arthrophryxiis, and the other the 

 type of a new species of Holophryxus, H. 

 giardi. An immature stage of Holo- 

 phryxus giardi was also obtained and is of 

 interest in being a stage not heretofore re- 

 corded in the development of the female 

 from the cryptoniscian larva to the adult 

 form. Both of these parasites are at- 

 tached to the dorsal side of the carapace 

 of the host with the head directed poster- 

 iorly. The male Holophryxus alasce-nsis 

 Richardson is also described for the first 

 time from a specimen obtained at Monterey 

 Bay. 



Leidya distorta (Leidy) Found on a New 

 Host: Harriet Richardson, Smithsonian 

 Institution. 



Specimens of Leidya distorta (Leidy) 

 found in the branchial cavity of Pachy- 

 grapsus transversus Gibbes, from the Ber- 

 mudas, were recently sent me by Professor 

 A. E. Verrill. This species has been re- 

 corded as found in the branchial cavity of 

 Uca pugilator. The fact that this parasite 

 has been found on a new host gives evi- 

 dence that this genus and species is not con- 

 fined to one genus and species of host. As 

 no descriptions or figures of this form have 

 been given since those published by Leidy, 

 the parasite is again described and figured, 

 as well as the young female, which is de- 

 scribed and figured for the first time. 



The following demonstrations were ex- 

 hibited : 



L. B. Walton: (1) The ideal dissecting 

 tray; (2) early stages of Eurypauropus 

 spinosus Ryder; (3) museum cataloguing; 

 accession and department catalogue cards. 



Henry F. Nachtrieb : (1) Early stages in 

 the development of the thymus of the pied- 

 billed grebe— reconstruction of one stage; 

 (2) the sensory ridges of the lateral line 



and the primitive pores of Polyodon 

 spathula. 



R. M. Strong: A litter of short-tailed 

 and tailless puppies. 



Thomas G. Lee: Early stages in the de- 

 velopment of Dipodomys and other 

 rodents. 



P. R. Lillie : Karyokinetic figures of cen- 

 trifuged eggs. 



S. 0. Mast : An electric thermo-regulator. 



Chai'les Brookover: Ganglion cells on 

 Pinkus's nerve of Amia and Lepidosteus. 



R. S. Sheldon: Medullated nerve fibers 

 in the olfactory mucous membrane of 

 fishes. 



W. L. Tower: (1) Demonstration case to 

 illustrate the evolution of the lineata 

 group of the genus Leptinotarsa, showing 

 forms that have been produced in experi- 

 ment and sports occurring in nature; 

 (2) demonstration case to illustrate the 

 results obtained in the production of sports 

 experimentally— arranged to show the re- 

 sults produced in the stimulated germ-cells 

 and the results from those not stimulated 

 in the case of the same parent; (3) demon- 

 stration case to show the results obtained 

 in the transplantation of Leptinotarsas 

 from one habitat into another and the 

 proof that they are different in the new 

 habitat as demonstrated by the behavior of 

 the modified and unmodified form when 

 crossed with a third species; (4) demon- 

 stration eases to illustrate results obtained 

 in the study of variability of dominance in 

 crossing. 



C. R. Bardeen: Abnormal toad and frog 

 larvEe from eggs fertilized by spermatozoa 

 exposed to the Roentgen rays. 



W. J. Baumgartner: A cheap sharp 

 microtome knife. 



Section F of the American Association 

 for the Advancement of Science was 

 organized at the Chicago meeting with the 

 following officers: 



