238 MiscellaneoiLS, 



MISCELLANEOUS. 



On the Reproductive Organs of Sertularia tamarisca. 

 By Prof. Allman. 



In a communication read in the Natural History Section at the 

 Leeds Meeting of the British Association, the author called attention 

 to the fact that Sertularia tamarisca — which, like most of the Hy- 

 droid Radiata, is strictly dioecious — presents the further remarkable 

 character of having its male and female gonophores (generative vesi- 

 cles) totally different in form, — an important fact as regards the 

 zoographical characterization of the species. 



The male gonophores appear to he those figured by Ellis in his 

 description of this species ; they are compressed somewhat obcor- 

 date bodies, with a short terminal tubular aperture. 



The female gonophores are far less simple in form ; they are oval 

 for about the proximal half of their length, and then become tri- 

 hedral with the sides diverging upwards, while the whole is termi- 

 nated by a three-sided pyramid. The sides of the pyramid are cut 

 into two or three short teeth along their edges ; and each of their 

 basal angles is prolonged into a short spine. 



The trihedral portion, with its pyramidal summit, is formed of 

 three leaflets, which merely touch one another by their edges with- 

 out adhering, so that they may be easily separated by the dissecting- 

 needle. They consist of the same chitinous material as that which 

 invests the rest of the gonophore, formed doubtless originally on the 

 surface of an ectodermal lamina. 



The male gonophore is traversed by a fleshy axis (blastostyle), 

 which gives origin to one or more sporosacs containing the sperma- 

 togenous tissue surrounding a well- developed spadix *. The sperma- 

 tozoa have an elongated body of a cylindrical form, with a long caudal 

 filament. 



On laying open the female gonophore, the oval portion of it is 

 seen to be occupied by a blastostyle, which gives origin to one or 

 more sporosacs entirely resembling^ the male sporosacs except in the 

 nature of their contents, which are here ova instead of spermatozoa. 



The oval portion of the gonophore terminates upwards by closing 

 round the remote extremity of the blastostyle, where it forms a ring 

 with tooth-like processes, by which the extremity of the blastostyle 

 is encircled. This oval portion constitutes the proper capsule of the 

 gonophore, and is the only part developed in the male. From the 

 summit of the blastostyle several irregularly-branched csecal tubes, 

 apparently com.municating with its cavity, are given off. They lie 

 altogether external to the proper capsule, and embrace a delicate sac, 

 within which are one or two ova in an advanced state of develop- 

 ment, each in a delicate structureless sac of its own, which is con- 



* The author proposed the term spadix to indicate the diverticulum 

 from the common cavity of the coenosarc, which in most of the Hydroid 

 Zoophytes extends into the centre of the sporosac, and round which the 

 generative elements (ova or spermatozoa) are developed. 



