<636 Palaeontologie. 



Lomaxi and L. ovo'ides, vvhich agree with considerable exactness 

 in form, and in the characters of the wall. Lastly, it is shown 

 that, there is a correspondence in certain morphological cha- 

 racters between the synangium of T. Scotti, and the seed 

 LaFenostoma. 



The Author proceeds next to a detaüed comparison of the 

 microsporangial sortis with the seed Lagenostoma, and arrives 

 -at the conclusion that the seed is derived from a synangium. 

 It is pointed out that the Chambers surrounding the nuceMus 

 seem to represent the sterile, sister sporangia of a synangium 

 surrounding the Single fertile sporange, the micropyle corres- 

 ponding to the original space between the tips of the sporangia. 

 The seed in fact is assumed to be a synangium, in which all 

 but one of the sporangia are sterile and form an integument to 

 the one fertile sporange, which has become a megasporange 

 with one large megaspore. We may imagine that one of the 

 sporangia of the sorus of 8 or 10 sporangia gradually evolved 

 megaspory, and that the remaining 7 or 9 sporangia became a 

 sterile envelope — a correlation in deveiopment which has many 

 analogies in the animal and vegetabie kingdoms. As soon as 

 one of the sporangia became a megasporange, the symmetrica! 

 arrangement of the sister sporangia would become an advantage, 

 and naturally follow. 



The origin of the vascular supply of the seed is discussed 

 in reference to this conclusion, and also the various theories 

 already put forward with regard to the Interpretation of the in- 

 tegument. It is pointed out that the synangium is a very an- 

 cient type of fern fructificatiim ; Scolecopteris, and other fossil 

 genera are mentioned in this connection. Attention is also called 

 to certain features exhibited by palaeozoic and Mesozoic seeds, 

 especially those of Bennettites The structure of the seed of 

 Beiiiicttites Morierei is regarded as very strongly confirmatory 

 of the homology of the seed with a synangium. That of Gne- 

 topsis elliptica, is also mentioned in this connection. In Bo- 

 tryopteris, a special case is cited from Renault of sterilizcd 

 sporangia in tufted sori. 



The following characters are regarded as suggestions of 

 sporangial origin of the inner integument in primitive seeds. 

 It is frequently compartmental , each compartment containing 

 large thin-walied cells as contrasted with the firmer peripheral 

 layers, and the peripheral wall is constructed of the same cha- j 



racteristic layers as are met with in many sporangia. Also the J 

 iorm of the base and apex of each compartment is often very % 

 similar to that of members of a synangium. In some cases 

 there is considerable freedom between the constituent compart- 

 ments, whose apices form the so-called tentacles around the 

 micropyle, and the compartments are comparable in size with 

 the nucelliis. Also the compartments vary in number in the same 

 way as the members of many Palaeozoic synangia. The inte- 

 gument of many of the seeds undergoes septicidal dehiscence 



