Linncean Society. 265 



The author then proceeds to describe the development of the spo- 

 rules. A transverse section of the involucrum when about the size 

 of a small pin's head shows it to consist of four integuments, con- 

 taining a mass of very delicate spongy compressible cellular tissue, 

 subdivided into four equal triangular portions by four lines radiating 

 from the centre. In the centre of each of these portions is a cavity, 

 and projecting into each of these cavities are a number of nipple- 

 like processes which are attached in each cavity to a common recep- 

 tacle, whilst this again is connected with an open rigid cellular 

 tissue that lies between the spongy tissue before described and the 

 involucrum, and serves as a connexion between the two. As the 

 involucrum advances, the spongy tissue recedes all round the four 

 cavities, which consequently become larger and afford more space 

 for the growth of the nipple-like processes. This recession of the 

 spongy tissue is not caused by the pressure of the growing pro- 

 cesses, for it is frequently in advance of them ; but it is produced by 

 a gradual condensation inherent to the tissue around the cavities 

 and along the radiating dividing lines, which, in fact, are nothing 

 more than this condensation, which at maturity is so complete that 

 the whole of the spongy tissue is condensed into four dissepiments, 

 dividing the cavity of the involucrum into four equal loculi. The 

 nipple-like processes are found upon a careful examination to be 

 hollow sacs with obscurely cellular walls — those which occupy the 

 lowest part of the involucrum being considerably in advance of the 

 upper ones. These sacs contain a quantity of grumous matter, and 

 a number, perhaps about ten, of soft rather opake pulpy bodies, 

 which are evidently compounded of four closely connected parts so 

 placed on each other as to form a cone with a triangular base. 



April 2. — The Lord Bishop of Norwich, President, in the Chair. 



Mr. Owen read a Paper on a New Species of the genus Lepido- 

 siren of Fitzinger and Natterer. The author commenced by advert- 

 ing to the first announcement of that anomalous animal, the Lepido- 

 siren paradoxa, as the type of a new genus of Perennibranchiate 

 Reptiles by Fitzinger at the meeting of the German naturalists at 

 Prague in 1837, and to its subsequent description by its discoverer 

 Dr. Natterer, the well-known South American traveller. 



With the generic characters assigned by these able German na- 

 turalists to their Lepidosiren, the species described by Mr. Owen 

 fully and closely agreed ; but it differed specifically in the greater 

 relative length of the head and rudimental extremities, and its much 

 smaller size. 



Ann. Nat, Hist, Vol.3. No. 17. June 1839. u 



