GENUS PROBOSCELLA. 549 



advanced state of decomposition. From L. pusillus, which it most closely resembles 

 in point of size, it may be distinguished by the relatively larger size of its adoral 

 cilia, by its more pointed anterior extremity, and by the absence of cuticular 

 striation. The extreme mobility or elasticity of this type would seem to surpass 

 that of any of the forms as yet referred to the genus. While occurring abundantly 

 in the open water, where its comportment corresponds with that of the species 

 previously described, numbers were found imbedded in the substance of the glcea- 

 film itself, and through which they were busily occupied in slowly boring their way 

 in a worm-like manner, each body adapting itself readily to every vacuole within this 

 matrix, and assuming the most contorted and fantastic shapes. One of the more 

 ordinary sinuous contours exhibited under these last-named conditions is represented 

 at PL XXVII. Fig. 67. Natation is usually accomplished in an even straightforward 

 direction, or through rotation upon its long axis. 



Lembus elongatus, C. & L. sp. PL. XXXII. FIG. 10. 



Body very narrow, -elongate, somewhat bent, sub-even throughout, about 

 seven times as long as broad ; oral aperture in the centre of the ventral 

 surface, oral and cuticular cilia fine and short, even throughout, a long, 

 recurved, buccal seta (margin of the undulating membrane) extending 

 forwards from the oral aperture to the anterior extremity ; contractile vesicle 

 large, postero-terminal ; anal aperture in front of the contractile vesicle. 

 Length 1-300". HAB. Salt water, Norwegian coast. 



This animalcule, originally described by Claparede and Lachmann * under the 

 title of Cyclidium elongatum, cannot be referred with absolute certainty to the genus 

 Lembus, although the figure given of it, as here reproduced, would appear to favour 

 such location. Its habits, as recorded by these authorities, differ considerably 

 from those of either L. velifer or the succeeding species, it remaining for the most 

 part stationary among vegetable debris, and forming within the same an irregular 

 tube-like excavation, into which it rapidly retreats at will. 



GENUS II. PROBOSCELLA, S. K. 



Animalcules free-swimming, highly flexible, elongate-lanceolate, or ver- 

 micular ; oral aperture ventral ; an elongate, undulating membrane extending 

 backwards from the anterior extremity to the oral aperture, associated with 

 a fringe of longer adoral cilia ; a slender, extensile, digitiform or snout-like 

 appendage produced from the apical extremity ; the posterior extremity 

 bearing one or more caudal setae. Inhabiting salt water. 



Proboscella vermina, Mull. sp. PL. XXVII. FIGS. 65 AND 650. 



Body elongate-clavate, compressed, seven or eight times as long as 

 broad, the posterior half cylindrical or subfusiform, more or less rounded 

 posteriorly, the anterior portion linear, about one-half the diameter only of 

 the posterior part, terminating apically in a short, flexible, curved, retractile 

 and extensile fingerlike process ; oral aperture ventral, subcentral, situated 

 close to the junction of the more inflated posterior and narrower anterior 

 regions of the body ; undulating membrane irregularly triangular, extend- 

 ing from the oral aperture to within a short distance of the anterior 



* ' Etudes sur les Infusoires,' 1 868. 



