GENUS S TEN TOR. 595 



thickly filled with minute blackish, yellow, and cofifee-coloured pigment- 

 granules ; endoplast spherical. Length of body when extended 1-96". 

 Hab. — Bog water. 



Stein embodies with this species the Stentor or Salpistes castanms of Strethill 

 Wright, with which it seems fully to agree, with the exception that, as observed by 

 the last-named writer, the animalcules are in the habit of exuding an independent or 

 common mucilaginous investing sheath, similar to that already described of S. Rceselii. 

 In shape and size this form most nearly approaches S. igneus, from which, however, 

 it may be readily distinguished by its more plastic character and the finer granu- 

 lation of its parenchyma, which never contains green chlorophyll-granules, though 

 more especially by the greater length in comparison with its breadth, which it 

 exhibits in its expanded state. In this latter respect it more nearly approaches 

 S. Roeselii, S. polymorpJms, and other previously described species. Stentor niger 

 has been obtained by the author in some abundance in bog water at Lustleigh 

 Cleave on the borders of Dartmoor. 



Stentor multiformis, Miill. sp. Pl, XXX. Figs. 8 and 9. 



Body moderately large, exceedingly plastic and variable in form ; ex- 

 panded peristome equal in width to about one-third or one-quarter of the 

 entire length of the body; the longitudinal intra-muscular bands of the 

 cortical layer coloured an intense blue or sea-green ; endoplast spherical or 

 ovate. Length of extended body 1-180". 



Hab. — Salt water ; social. 



This marine type of the genus Stentor was first described by O. F. Miiller under 

 the title of Vorticella midtiformis, and has since been rediscovered and investigated 

 by Stein. In aspect and colour it most nearly resembles the fresh-water Stentor 

 ccBruleiis. It is, however, usually of much smaller size, and has at the commencement a 

 simply oval or spheroidal endoplast. It further exhibits a greater range of variation 

 in external contour than is associated with any other hitherto described type of this 

 genus. Among these protean diversities of outline, that depicted at PI. XXX. 

 Fig. 8, is, perhaps, the most remarkable, the body as a whole being in this instance 

 flask-shaped and produced anteriorly into a long, slender neck, with the expanded 

 peristome-border equal to about one-third only of the inflated posterior portion. 

 Under the condition of complete extension it rarely, if ever, appears to assume that 

 elegant trumpet form so characteristic of the ordinary species, and in which, as a 

 necessary consequence, the peristome-border represents the widest diameter, but is 

 more usually either clavate or pyriform. 



Stentor auricula, S. K. Pl. XXX. Figs. 6 and 7. 



Body colourless, in extension shortly trumpet-shaped or turbinate, the 

 width of the expanded peristome equal to, or even exceeding, the height 

 of the body, the latter tapering very abruptly towards its posterior 

 extremity or point of attachment ; the peristomal border interrupted on 

 its ventral aspect by a deep cleft or sulcus which gives to the entire 

 structure a bilobate or auriculate appearance ; endoplast ovate, subcentral. 

 Length of extended body 1-130". 



Hab. — Salt water. 



This species is readily distinguished from all previously described forms by the 

 great breadth of the peristomal area in proportion to the length of the body, com- 

 bined with its peculiar lobate contour. In this last respect it may be said to make a 



K 2 



