14 Transactions of the Society. 



case. Although H. perforata has occasionally been seen feeding 

 it has always been difficult to get a dorsal or ventral view of it, as 

 its shape causes it to fall over on its side. Dead examples with 

 the corona expanded do not shew the disks separated. //. perforata 

 has small spurs, which were not seen till after the original descrip- 

 tion was published, and it has a short "tail." 



Mr. Bryce informs nie that he believes a large proportion of the 

 species of Habrotrocha secrete cases. It may be that all do so for 

 temporary use at certain times. Many tube-makers are quite com- 

 monly found without tubes. H. pusilla is especially liable to desert 

 its case. 



Habrotrocha appendiculata sp. n. Plate I. figs. Aa-Ab. 



Specific Characters. — Small ; trunk broad, coarsely stippled ; 

 preanal segment bearing two large divergent processes on its poste- 

 rior angles ; head relatively very small ; corona a little wider than 

 the neck, disks close together ; collar prominent ; teeth many, 

 diminishing in size ; foot short, spurs narrow, acute, divergent, 

 without interspaces. 



General Description. — Length when feeding 280 p, diameter of 

 corona 40 p, collar 35 p, neck 30 p, central trunk 90 p, across the 

 " tails " of the preanal <>0 p, length of spur 12 p. The central trunk 

 is very broad and is regularly plicate. The stippling consists of 

 pellucid dots, not papilla? — it does not extend to the neck or foot. 

 What appears to be the preanal segment is 2-lobed, and bears two 

 pairs of dorsal skinfolds separated by a transverse fold. It may 

 consist of the 4th-central and preanal. The " tail "-processes are 

 large, about 12 p long, conical, subacute, not stippled. The anal 

 is short and diminishes very rapidly. The foot is 3-jointed, the 

 first joint as broad as long. The neck segments diminish rapidly 

 from the trunk forwards. The widest, next the trunk, usually con- 

 tains the mastax when feeding. The upper lip forms a pointed 

 arch. The teeth are like those of H. constricta — eight or more can 

 be counted — the front one is thickest, and those behind diminish 

 rapidly in size till they are as fine as the striae which cover the 

 whole surface of the ramus (except where the teeth are) in most 

 Bdelloids. It is thus difficult to say what is the exact number of 

 teeth in species like H. constricta. 



H. appendiculata looks very like H. microcephala, as may be 

 seen by comparing the figures (16). The most obvious differences 

 are the smaller number of teeth in H. microcephala, and the tail- 

 processes of H. appendiculata. The corona of H. microcephala is 

 much smaller, the disks are angled, the collar is not prominent, the 

 spurs are shorter. 



The resemblance of H. appendiculata to H. microcephala is 

 superficial — its real affinity is with H. crenata (14). That species 



