154 G. T. HARRIS, COLLECTION AND PRESERVATION OF THE HYDROIDA_ 



Plumularia pirmata. 



The Plumulariidae are somewhat difficult for the beginner to> 

 separate, owing to the superficial resemblance of one species with 

 another. The most -trustworthy means of separating the species 

 is by a careful observance of the nematophores and distances of 

 the calycles. In P. pinnata the nematophores are very minute, 

 and lack the pronounced calycle present in other species, and. 

 are one below each hydrotheca. The gonothecae also, when 

 present, help materially in distinguishing the various species. 

 In the present species they are ovate, with spinous projections 

 on the top. 



Plumularia setacea. 



It somewhat resembles the former species, but the nema- 

 tophores are very different, being of superior size and differing in 

 number. The gonothecae are quite different, being flask-shaped ; 

 their axillary position also is an aid to diagnosis. 



Plumularia echinulata. 



In this species the pinnae have an unmistakable arched form 

 which does not occur in the others. The nematophores are 

 smaller than in P. setacea, and one nearly always occurs in the 

 axils of the pinnae. The gonothecae, however, when present 

 readily determine the species. 



Plumularia similis. 



This appears to be very near the former species (P. echinulata), 

 but the gonothecae are totally dissimilar, being without the 

 spinous projections. 



Plumularia halecoides. 



A minute species, and easily overlooked, The polypites have- 

 been compared to an hour-glass in shape. The gonothecae are 

 transversely ribbed. Nematophores very minute and difficult to 

 detect. 



[The above notes are intended for use with a series of slides 

 presented to the Cabinet by Mr. G. T. Harris.] 



Journ. Quekett Microscopical Club, Ser. 2, Vol. XII., No. 73, November 1913. 



