BARDWICKE'S SCIENCE-GOSSIP. 



271 



should happen to be transmitted to some male 

 descendant. This might, of course, fail to occur, as 

 is shown by the existence of such well-established, 

 but unisexual varieties as Helicc and Valczina in our 

 own insect fauna ; but it seems unreasonable to doubt 

 that its occurrence would be more or less likely. In 

 the main, then, I think Mr. Holt right in his 

 limitation of the true scope of sexual selection : but 

 it seems to me possible that a species might be 

 formed by sexual (in co-operation with natural) 

 selection, where the peculiarity admired in the 

 original male, though associated with qualities of 

 direct advantage to him, is not in itself of such 

 advantage. ' 



C. B. Moffat. 



OX SOME MOSS-DWELLING CATHYP- 

 NADjE; WITH DESCRIPTIONS OF FIVE 

 NEW SPECIES. 



By David Bryce. 



IN my last communication I described two species 

 of Cathypnadae, which I had found in some 

 number, in water obtained by squeezing handfuls 

 of wet sphagnum. I now furnish descriptions of 

 five more species of the same interesting family, also 

 found associated with this and other wet-loving 

 mosses. Of these new forms, the two species of 

 Monostyla are the most important. 



The genus to which I have referred them, has 

 been an extremely well-defined one, possessing, in 

 the single, more or less styliform toe, an obvious 

 characteristic by which its members are readily to 

 be distinguished from the other Cathypnadse, and 

 the variations exhibited by the various species, have 

 ranged between comparatively narrow limits. Both 

 the new forms step outside the old lines, and in two 

 very distinct directions. In the first, the styliform 

 toe, in place of being furnished with the single claw, 

 which normally terminates it, is provided with a pair 

 of claws set side by side, yet slightly diverging, and 

 apparently incapable of motion independently of each 

 other, or of the toe. The two claws seem to indicate 

 a connecting link with the genera Distyla and 

 Cafhypna, though whether the structure marks an 

 advance towards, or a retrogression from these, it 

 would probably be rather unprofitable to discuss. 



The second species is still more surprising, for it 

 shows a relationship to quite another family, in 

 having a corona protected by the glassy hood-like 

 shield, so characteristic of the Colurida?. 



Among the new Distylae, the species agilis is note- 

 v, orthy, on account of its minute size, the extreme 

 delicacy of its parts and the untiring vivacity of its 

 movements. 



All these species, and many others will live for 

 weeks and months in sphagnum, kept in a cool 

 place in a tightly corked bottle, without any water 

 save that clinging to the moss 'when gathered. I 



had, up to the end of May, one such bottle con- 

 taining sphagnum, collected in August, 1891, at 

 Sandown, Isle of Wight, from that little patch of 

 boggy ground beyond the Waterworks, where the 

 sundew grows in profusion. When first put into the 

 bottle, the moss was wet, as it usually is, and 

 remained wet to the touch, but no more. It had 

 considerably decayed, and had become brown and 

 sodden. Yet if a stem were placed in water, one 

 might at once see several species of Rotifera in full 

 activity. In May the most numerous was Distyla 

 clara, but that species has now disappeared, although 

 other species of Rotifera are (in October) still 

 represented. There is here, no question of the 

 creatures having been partially dried, and resuming 

 activity on being moistened with water. Nor can 

 we suppose that the Distylfe seen in May, were the 

 identical specimens in the moss wrlen gathered. 

 The point of interest is, that, with the exceeding 

 scanty supply of fluid afforded by the wet moss, and 

 living probably, directly or indirectly, on the 

 nutriment afforded by the decaying vegetable matter, 

 such delicate creatures as these minute rotifers have 

 been able, not only to survive, but even to continue 

 their respective species for many generations. With- 

 out doubt, the extremely slow decay of the moss is 

 in their favour. Ordinary water-plants, kept in a 

 corked bottle with but little water, would probably 

 ferment and quickly go black, and I think that no 

 rotifer could endure that. 



On the other hand, I have hitherto but rarely 

 induced any of these forms to live more than a day 

 or two in water, in which I had " washed " thread? 

 of moss. So difficult is it to hit the happy medium, 

 between rendering the water foul and not providing 

 it with sufficient nutrient matter, or between poison- 

 ing and feeding the rotifers. 



On one occasion I was more fortunate ; a few 

 individuals of Distyla inermis, survived their plunge 

 into the ocean of the zoophyte trough. A colony 

 was founded, and throve, until I depopulated it by 

 emptying the trough and forwarding the contents to 

 a correspondent. I refilled the trough with water, 

 and in a few days began to find the species again, 

 hatched out from eggs fastened here and there to the 

 glass. In a fortnight or so, I was able to send off a 

 second parcel, and I was hoping to get a third, but 

 about this time the trough began to leak, and one 

 evening I found it empty and dry, 



Distyla clara, n. sp. 



Sp. Ch. — Form a long ellipse. Lorica stiffly 

 membranous, without markings, very transparent. 

 Head broad and blunt. Anterior part of trunk 

 usually distinct. Toes nearly one-fourth of total 

 length, slenderly blade-shaped, tapering, without 

 claw or shoulder, slightly decurved. Brain short ; 

 eye absent. Dorsal plate moderately arched. 



The broad blunt head, the almost simple tapering 



