1892.] On the Shoulder Girdle in Ichthyosauria, $c. 471 



III. "On the Shoulder Girdle in Ichthyosauria and Sauro- 

 pteiygia." By J. W. Hulke, F.R.S. Received April 11, 

 1892. 



(Abstract.) 



The author discusses the structure of the shoulder girdle and the 

 homologies of its several parts in these families. He shows that the 

 alleged existence of a precoracoid in the Ichthyosauria rests on an 

 insufficient foundation ; offers proofs that in Plesiosauria the anterier 

 ventral ray is not only theoretically but actually precoracoid ; and 

 also that the dorsal ray in the girdle is homologous with the shoulder- 

 blade in Testudinata and other Reptilia. 



IV. " On the Embryology of Angiopteris eveeta, Hofm." By J. 



Bretland Farmer, M.A., Fellow of Magdalen College, 

 Oxford. Communicated by S. H. Vines, M.A., F.R.S. 

 Received March 28, 1892. 



During a recent visit to Ceylon I took the opportunity of collect- 

 ing young plants and prothallia of Angiopteris evecta, with the view 

 of working out the embryology of this type of the eusporangiate 

 Filicineae, since the development of the embryo is not as yet known 

 in any member of this group. 



Most of my specimens were obtained from clay banks in the 

 vicinity of Peradeniya, where the plants are not uncommon. The 

 prothallia are easily distinguished from those of other Ferns by their 

 somewhat orbicular shape, with crenate edges, as well by their 

 strikingly deep-green colour. They resemble the thalli of Anthoceros 

 rather than a common Polypodiaceous prothallium, and indeed are 

 not easily distinguished from the former when the two plants are 

 associated on the same bank, as is frequently the case. 



The germination of the spore and the development of the prothal- 

 lium have been described by Jonkman,* who also observed the 

 formation of the sexual organs. The antheridium is formed from a 

 superficial cell of the prothallium, which divides by a wall, parallel 

 to the surface, into an outer shallow cell and an inner cubical cell. 

 The former, by walls at right angles to the free surface, gives rise to 

 the cover cells ; while the inner one, by successive bipartitions, 

 originates the aritherozoid mother-cells. This Fern is a very favour- 

 able type for exhibiting the development of the antherozoids from the 

 nucleus of the spermatocyte, on account of the relatively large size 

 of the structures in question. 



* * De geslachtsgeneratie der Marattiaceeen,' door H. F. Jonkman. 



