ON LAFCEA DISPOLIANS SP. N. HI 



derm is thick. The endoderm of the hypostome is modified, 

 and consists of tall^ narrow, columnar cells, which are exceed- 

 ingly granular and stain very readily (fig. 8, e, h). 



Nematocysts, variable in size, the commonest variety being 

 about 3'5 /.t in length and l"o /n in breadth. The endoderm tube 

 of the coenosarc, when the parasite is outside of the host, just 

 as in the case of the Sertularia, contains on one side many 

 globules of a fatty nature. This character is, however, more 

 marked in the Sertularia host (figs. 1, 2, and 3). The 

 ectoderm of the coenosarc of the hydrorhiza may contain 

 nematocysts (fig. 3, n). 



EXPLANATION OF PLATE I, 



Illustrating Dr. Ernest Warren's paper "On Laf oea dispolians 

 sp. n., a Hydroid Parasitic on Sertularia bid ens Bale." 



Fig. 1. — X 325. Cross-sectiou along the Hue 1. 1 (see Text-fig. 2) 

 whowing parasite inside (P. i.) and outside (P. o.) tlie host. p. H. is peri- 

 aarc secreted by the host and shutting off the parasite. 



Fig. 2.— x325. Cross-section along the line 2, 2 of Text-fig. 2. 

 Showing the parasite separating itself from the perisarc-wall of the 

 host. 



Fig. 3. — x 325. Cross-section along the line 3, 3 of Text-fig. 

 showing parasite completely sepai'ate from the perisarc-wall of host. 

 The imrasite is surrounded by a tube of perisarc {p. H.) secreted by the 

 host. 



Fig. 4. — x 325. Cross-section along the line 4, 4 of text-fig. cutting- 

 through the liydrothecai of the two sides. The parasite is separated by 

 perisarc-partition (2). H.) secreted by the host. The perisarc of the 

 parasite {p. P.) is exceedingly thin. In the hydrotheca of the left side 

 the hydrorhiza-sac (/(. s.) is seen, and on the right side a cross-section of 

 the base of the polyp (6. H.) is also shown. 



Fig. 5.— x 325. Cross-section along the line 5. 5 of Text-fig. cutting 

 through the basal aperture of the hydrotheca. The parasite is seen 

 passing into the hydrotheca. A sheet of perisarc (p. H.) secreted by the 

 host separates the parasite from the ca?nosarc of the Sertularia. 



