1883. 179 IDale. 



The blastoderm interpreted at an atavistic form, was held to be an impor- 

 tant confirmation of the theory put forward by His and Rauber, according 

 to which the vertebrate embryo arises by concrescence of the two lateral 

 halves of the germ-ring. The objections made to this theory by Balfour 

 were reviewed, with a view to showing that they presented no serious diffi- 

 culties to the acceptance of the concrescence theory. 



Mr. Whitman maintained that Balfour's objections were not broad 

 enough to cover his own theory of the origin of the vertebrates from anne- 

 lids, — a theorj' which gave us a right to expect some fundamental agree- 

 ment in their modes of development. This agreement, he contended, was 

 seen, first, in the origin of the embryo from a germ-ring, by the coalescence of 

 the two halves along the axial line of the future animal ; and secondly, in the 

 metameric division, which followed in the wake of the concrescence. The 

 theory of the annelid origin of the vertebrates was inconsistent with the 

 denial of the concrescence theory, since concrescence of the germ bands is 

 a well established fact for both chaetopods and leeches. 



The theory of differentiation set up by Balfour in opposition to that of 

 concrescence entirely ignored the annelids, and offered no explanation of 

 the uniform relations of the embryo to the germ-ring. 



Dr. S. Kneel and read a number of notes made in travelling 

 through the Philippines, and showed and presented a large number 

 of specimens collected in many localities. Among the most inter- 

 esting was a fine specimen of the snout of a saw-fish, which was 

 taken in fresh water, 20 m. from the sea near Manilla. Dr. Knee- 

 land thought that the saw was wrongly supposed to be an offen- 

 sive weapon, but was more probably used in throwing up the 

 mud and sand of the shallow waters in which the fish lives, in 

 search of molluscs and cray fish. Among the other specimens 

 were many fossils and a fine collection of woods of the Philip- 

 pines. Dr. Kneeland also described the geysers of Tiwi, and pre- 

 sented a series of volcanic products from Mayon and also from 

 Aetna and Vesuvius. 



The following paper was read : 

 A CONTRIBUTION TO THE GEOLOGY OF RHODE ISLAND 



BY T. NELSON DALE. 



The Island of Aquidneck, which includes the townships of 

 Newport, Middletown and Portsmouth, R. I., has been the object 

 of no little study on the part of geologists. Dr. C. T. Jackson, 

 Pres. Edward Hitchcock, and Professors C. H. Hitchcock, W. B. 



