INVEETEBKATA, CRYPTOGAMIA, MICROSCOPY, ETC. 817 



truded, though it may sink below it, and may become detached from 

 the thcca at various points. The contractile vesicle is only momen- 

 tarily seen. 



This form differs from the Acinetinse in possessing a tentacle 

 which is never retracted into the body wholly or in part, as is the 

 case with the suckers in that group, but which agrees, with the 

 exception of the absence of cirrhi, with that of Ojphryodendron. Both 

 forms must be kept distinct from that family. 



Acinefa tiiberosa Ehrb. (Figs. 5 and 6, e,f) offers a good example 

 of the great affinity of its order with the Infusoria and disagreement 

 with the Rhizoi)oda, the characters of the gemmje giving grounds for 

 the one, and the distinctness from the rest of the body and the special 

 character of the suckers for the latter inference. The variations in 

 its colour are due to the presence of pale yellow, green, or orange 

 granules. Frequent contractions of the sarcode remove these granules 

 from different points which are thus left transparent; the narrow 

 portion, however, between the two tubercles (g, g) is almost constantly 

 thus transparent; it contains the one or two contractile vacuoles; 

 but the central part of the body is generally the most granular, and 

 is marked off from the lateral portions by two longitudinal ridges on 

 each side of the shell ; these ridges are absent in A. patula (Fig. 4), 

 hence the difference in the grouping of the suckers in the two species, 

 the body not being divided into separate areas. A species found in 

 stale sea-water had the lower end of the shell rounded; the upper 

 angles presented, instead of two tubercles, simply two perforations 

 of the shell. 



Trichodina Scorpence sp. n. (Figs. 7 and 8) does not exceed half 

 the size of T. i^ediculus auctt. ; it occurs on the branchiae of fish of 

 the genera Scorpena and Trigla. It is disk-shaped, the ventral side 

 concave, a narrower dome-like mass (a) rising above the disk (<■) ; 

 the only cilia present consist of a ring of stout ones (b) projectin« 

 upwards from the upper edge of the disk, and one of fine ones {d) in 

 a corresponding position on the lower side, the latter marking the 

 margin of the denticulated plate described as " organ of fixation " by 

 Clai)aredc and Lachmann. This organ consists of a narrow circle, 

 into the centre of which project numerous straight teeth, whilu the 

 circumference is lined by curved ones (Fig. 8). The body and this 

 organ especially undergo great changes after death, which occurs soon 

 after that of the host. 



Gemmation of Podophrya Lynghyei Ehrb. (Plates XVIII. and 

 XIX., Figs. 9-14). Tlie body substance of this species, wrongly 

 referred to P. gemmipnra by Hcrtwig, is not separable to the 

 sliglitest extent from the shell or theca, though this is readily 

 distinguishable from it by its contours, its folds, and its resistance 

 to agents which destroy the former. The nucleus is elongated and 

 curved, often bi- or tri-furcatc. In encysted individuiils the sub- 

 stance of the body is withdrawn slightly from contact with the cyst. 

 The peduncle (a, h) has a very delicate wall, and is homogeneous, 

 rarely manifesting a longitudinal striation. 



The external buds commence as a liyalinc cup of sarcode on the 



VOL. III. \\ H 



