38 



canus). He had found the yolk, not surrounded by an amnios, 

 but resting in the centre of an area vasculosa, and presenting, in 

 its early development, other peculiarities only known to exist in 

 the egg-laying vertebrata. He considered Plagiostomes a dis- 

 tinct class of animals from fishes, and he thought it probable that 

 Cyclostomes should also be separated as a class. He could not 

 refer to one class animals developed in such different modes. 

 The number of classes into which the animal kingdom is divided 

 — into six by Linnteus, into sixteen by Cuvier, and into twenty- 

 nine by Ehrenberg — shows that anatomical differences are in- 

 sufficient for a proper determination of classes. He proposed 

 that the general plan of structure be a test for types, and the 

 manner in which this plan is developed the test for classes. 



Prof. Agassiz, in alluding to the probability of a fecundation 

 of the egg whilst in the ovary, a question discussed at the last 

 meeting, stated that Dr. Weinland had found, in the viviparous 

 Zoarces anguillaris, that the ovarian bag (Graafian Vesicle) of 

 the mature eggs was not a simple sac, but a double one ; and 

 further, that this double sac was not continuous over the com- 

 plete circumference of the egg, but that a disc of considerable 

 size remained uncovered at the upper part, where the spermatozoa 

 might come in contact with the yolk membrane. Dr. Weinland 

 had also found the same condition in the skates and turtles. 

 Pi'of. Agassiz thought that the same organization would be found 

 in all Vertebrata. 



Mr. Charles Stodder informed the Society that Mr. 

 Samuels, the Society's Collector, had returned from 

 California. 



Mr. Samuels reports that he arrived at Petaluma, 

 California, December 1, 1855, and left, in consequence of 

 ill health, on the 4th of July, 1856. He explored the 

 country, and collected specimens, in the distance of 

 twenty miles east, north, and west of Petaluma, being 

 portions of the two counties of Sonoma and Marine. 



He has sent to the Smithsonian Institution eleven 

 large boxes, containing between 900 and 1000 species, 

 and many thousand specimens. 



