HARDWICKE'S SCIENCE-GOSSIP. 



57 



rnustela, Stepkanops stylatus, Monostyla arcuata, and 

 Mr. Bryce has even seen several impoverished- 

 looking Floscules living under these, for a Rhizotan, 

 remarkable conditions of environment. Amongst 

 the water-loving Sphagnum are to be met with, in 

 addition to the forms already mentioned, Philodina 

 macrostyla, Rotifer vulgaris, Macrotrachela Roeperi, 

 M. reclusa (these last two parasitic within the cortical 

 cells of the Sphagnum-stems), Notops hyptopiis, 

 Diaschiza pceta, Dislyla plexitis, D. depressa, Mono- 

 styla lunaris, M. cornuta, Colnrus caudatus, and 

 Anuria serrulate. 



With these introductory remarks, I proceed to the 

 description of two new forms which have occurred 

 to me from among terrestrial mosses during the past 

 few months. 



Macrotrachela multispinosa. 



The genus Macrotrachela was instituted by Mr. 

 Milne,* to include those three-toed Callidina; in 

 which, besides the general absence of eye-spots, the 

 whole of the post-intestinal portion of the body (i.e. 

 from the cloacal orifice to the extremity of the foot) 

 is constantly of less length, often very markedly so, 

 than the pre-intestinal region (i.e. from the mastax to 

 the extreme front of the body) ; the foot is therefore 

 necessarily very short, and its spurs are of notably 

 minute size. All are oviparous species. Dr. Hudson 

 does not (or did not up to 1SS9) recognize this genus, 

 and refuses to separate it from the older Callidina, 

 under which latter generic name several of Milne's 

 species of Macrotrachela are included in the " Sup- 

 plement"! It is true that no better generic distinc- 

 tion between the two has yet been diagnosed than the 

 seemingly arbitrary one of relative lengths above 

 given, but it is no less true that all the species of 

 Macrotrachela agree closely with each other in 

 regard to general appearance and structure, and in 

 habits, and appear to constitute a very satisfactory 

 and distinct genus by themselves. The mere non- 

 presence of eyes is no longer a sufficient character on 

 which to base a rotiferous genus, as was done with 

 Callidina. One of the Macrotrachelas (M. Roeperi) 

 has itself a pair of distinct frontal red ocular spots, 

 and the neighbouring genus, Adineta, originally 

 instituted from the knowledge of a single species 

 with the generic character "eyes absent," now 

 presents the anomaly of a second species, since 

 discovered, possessing very conspicuous visual 

 organs. 



While it is thus apparent that the present genera 

 of Bdelloida will need revision in the future, when 

 further discriminating characters may have been 

 detected, the general, and I think the increasing, 

 feeling among rotifer-workers is that the genus 



'Proc. Phil. Soc. Glasgow," 1883-6. 



' The Rotifera; Supplement, 1889." Longmans. 



Macrotrachela is a good one, and for these reasons I 

 adopt it here. 



The present species occurred to me amongst some 

 Jungermannia gathered from damp ground in a 

 swampy, wooded hollow at Wanstead Park, Essex, 

 in October last. It is, for its genus, a large bulky 

 species, and is rendered very distinct from any of its 

 fellows by the curious long chitinous spines or bristles 

 with which its integument is furnished, and which, 

 when the creature is retracted, (Fig. 26), give it a 

 very unapproachable aspect. These bristles are not 

 scattered haphazard over the surface of the body, but 

 are arranged in definite order at particular spots. A 

 half-whorl of eight spines occurs upon the ventral 

 surface of the thicker basal portion of the neck ; of 

 these eight (Fig. 30), the outer or most marginal pair 

 are very long and directed downwards, the next pair 

 are shorter, and the central four mere tiny points ; 

 together they, form a spinous half-collar round the 

 neck, and possibly aid in locomotion by catching on 

 to the surface over which the animal is crawling. No 

 trace of spines is seen upon the dorsal surface of the 

 neck. 



Upon the trunk the spines are all confined to the 

 dorsal and lateral surfaces, the venter being quite free 

 from these appendages — unlike the neck, where, as 

 just stated, the reverse is the case. Numerous 

 bristles, those nearest the front of great length, occur 

 towards the lateral aspects of the trunk, arranged 

 along two longitudinal submarginal ridges on each 

 side ; a third, more ventral, and less distinct ridge, 

 runs parallel with these, on each side, and bears 

 several very minute blunt projections. Across the 

 middle of the back runs transversely an elevated 

 ridge, which bears four short conical blunt spines at 

 the points where the longitudinal ridges of the trunk 

 meet the cross-ridge— in addition to those longer 

 lateral spines where it joins the lateral longitudinal 

 ridges. The transverse ridge, and its spines, are 

 best observed in a retracted individual (Fig. 26), 

 when the points are seen to project stiffly upwards as 

 a defence to the back ; when the creature is fully 

 extended, as when crawling, the ridge itself is almost, 

 though not fully, obliterated, and its spines likewise 

 become less distinct. A couple of small spines, close 

 together, occur upon the median line of the back, in 

 front of the ridge. Further back, the trunk presents 

 an always conspicuous transverse fold of the integu- 

 ment at a point where, in retraction, a sudden 

 diminution in its width sets' in. This fold bears 

 dorsally some five minute, pointed projections, 

 sometimes placed at unequal intervals, as well as a 

 pair of larger spines on each side terminating the 

 lateral longitudinal ridges. 



Yet more to the rear, upon the narrower portion of 

 the trunk, occur, also dorsally, two cross-rows of 

 short, sharp, conical spines, five spines to each row, 

 the outer or most lateral one on each side being 

 slightly larger than the median three, in each case. 



