152 NOTES ON PLYMOUTH HYDROIDS. 



sections were made of the male gonophores. It may be, however, that 

 my specimens were too near maturity to furnish couchisive evidence 

 in this matter. In living specimens a division of sperm-cells with 

 partially-developed flagella was observed in the ectoderm. 



Asexual multiplication of P. pinnata. On April 23rd several colonies 

 of this species were brought in, which were peculiar in having the 

 ends of a number of hydrocladia greatly elongated, destitute of hydro- 

 thecse and nematophores, and distinctly clavate at the tips. Such 

 specimens were brought in almost daily for some time, whenever the 

 boat went out for collecting. The first colonies found were isolated 

 and kept under observation. They rapidly increased in length, and the 

 terminal turgescence became more prominent. In three or four days it 

 was noticed that these enlarged ends were forking and commencing to 

 branch. 



In about a week after the first specimens were noticed, it was 

 found that the side of the jar in which the colonies were confined was 

 marked with closely adhering thread-like filaments, which, on exami- 

 nation, proved to be the greatly produced hydrocladial extensions 

 mentioned above, and they were still connected with the colonies from 

 which they sprung. From these adherent extensions were growing 

 new colonies of P. pinnata in various stages of development. 



After a time the connection between the parent colonies and the 

 young was severed by atrophy of the connecting hydrocladial extension, 

 rootlets were put forth from the adherent portion or end of the original 

 hydrocladia, and thus young and perfectly independent colonies were 

 produced which grew rapidly during the next few weeks. Another 

 group of colonies showing the hydrocladial extensions was so placed 

 that the extensions could not touch the sides of the bottle in which 

 they were kept. In this case the hydrocladia grew and forked as 

 before, and new colonies arose from the forked ends of the hydrocladia. 

 The parent stalks afterwards died and fell to the bottom, giving the 

 young colonies a chance to attach themselves to the glass. 



This process reminds one so forcibly of the sending out of stolons 

 from which new shoots arise, as seen in many plants, that I have pro- 

 posed the name of stoloniferous reproduction for the asexual multipli- 

 cation of P. pinnata as above described.* It is the first recorded 

 instance of the kind among the Hydroida so far as I can find, although 

 it bears considerable resemblance to the fissiparous formation of frus- 

 tules as recorded by Allman.f 



Plumularia halecioides, Alder. This minute Plumularian was 

 found parasitic on Antcnmdaria. The gonosome was not present. 



* See American Naturalist, November, 1895. 

 t Oymnohlastic Hydroids, p. 152. 



