433 Proceedings of Scientific Societies. [May, 



He also spoke of an Arceuthobium (mistletoe) from the Pacific 

 coast, the seeds of which were forcibly expelled to some distance. 



Mr. Ryder described Licnophora cohnii Clap., a ciliated proto- 

 zoan found on a hydroid at the mouth of Chesapeake bay. The 

 hydroid was parasitic on the shell of a bivalve mollusk inhabited 

 by a hermit crab. 



Oct. 25.— Mr. Pike made a communication upon the celebrated 

 insect-bearing deposits of Mazon creek, Illinois. These fossils are 

 usually found in nodules of blue shale. 



Nov. 1.— Mr. Ryder stated that efforts had been made during 

 the last two summers to delay the development of fish eggs with 

 a view to transportation. These experiments were only partially 

 successful. At a temperatnre of 53 development proceeded nor- 

 mally, but more, slowly than usual, up to a certain point, when a 

 fungus formed upon the egg membrane. Temperature slightly 

 lower than 53 caused abnormal development, and 45 proved 

 fatal. Professor Brooks had found in the case of oyster eggs that 

 the phenomena of segmentation and nuclear division were ryth- 

 mical, and Mr. Ryder held that there was a direct relation between 

 these phenomena and heat as a mode of motion. 



Nov. 8.— Mr. Meehan said he had lately found Robinia viscosa, 

 which he believed had never been collected by botanists since its 

 description by Michaux, growing abundantly in gardens near the 

 Delaware Water Gap. It was said to have been brought from the 

 neighboring mountains. The plant produced a multitude of 

 flowers, but very few seeds. The rose acacia of the nurseries has 

 never been known to produce seeds. 



Mr. Ryder described the development of Hippocampus. The 

 quadrate, hyo-mandibular, and symplectic cartilages are largely 

 developed, the intestine is provided with a curious valvular 

 arrangement at its posterior end; and the plates, which ard 

 much fewer than in the adult, are developed as conical caps 

 immediately under the epithelium. 



Mr. Potts indicated a new species of sponge under the name 

 of Mayenia f.mberiformis. Sponges occur only in flowing, drink- 

 able water. He "had found from four to six species in every 

 stream he had examined. 



Nov. 15.— The Rev. Dr. McCook spoke of the methods of 

 escape practiced by orb-weaving spiders when thrown into the 

 water. Some apparently formed a little raft of web for their 

 hinder feet, and oaddled ashore with their fore feet; while another 

 further out allowed threads to float upwards from its spinnerets, 

 and was wafted ashore by the wind. These two methods were 

 both probably instinctive. , 



Nov. 22.— Mr. Ryder gave the results of his studies of the 

 division of cell nuclei. Dr. Horn described the peculiar struc- 



