2 68 



HARDWICKE'S SCIENCE-GOSSIP. 



says : "the wide but thin wing-like expansions of the 

 dorsal plate are very conspicuous by their glassy 

 clearness and by their peculiar form." These wing- 

 like expansions, however, in my living specimens, 

 were always decurved, and when seen end-wise, 

 reminded one of the valves of Ptcrodina valvata. It 

 was very rarely that they presented a full dorsal view, 

 the more general being a latero-dorsal one, when one 

 of the "wings" was clearly exhibited. It will be seen, 

 from Fig. 142, that the dorsal outline of living speci- 

 mens, is much like that of Mr. Gosse's N. thallasia, 

 but that dead specimens, Fig. 3, which were numerous, 

 clearly showed the broadly ovate form of N. scapha. 

 Now both these species were sent to Mr. Gosse, by 

 Mr. Hood, in the same bottle of sea-water, from a 

 tide-pool in the Frith of Tay. Is it possible that 

 N. thallasia was named from a living, and N. scapha 

 from a dead specimen ? Mr. Gosse's large experience 

 forbids such a supposition. Unfortunately, my speci- 

 mens were intolerant of confinement, most of them 

 dying the day after their capture, even when kept 

 in a good-sized bottle in which Brachiomis rnbens and 

 other Rotifera lived and bred for many weeks. I 

 sent a tube to my friend, Mr. Gosse, but they were 

 dead on arrival. He wrote me that he could not 

 distinguish the form from N. scapha, but must see 

 living specimens before giving an authoritative 

 opinion. Subsequently I sent him others, immedi- 

 ately after their capture, which were more fortunate, 

 and I have been pleased to hear that they arrived 

 alive. He writes me that " its capture is the most 

 interesting as a fact, for here it was, indubitable, yet 

 occurring in fresh water for the first time in my 

 experience." I think it very probable that all the 

 forms which are considered as marine, are also in- 

 habitants of fresh water, and would be discovered if 

 they were carefully looked for. There can be no 

 doubt but that millions of the Rotifera are constantly 

 carried down to the sea, for although rivers are not a 

 habitat where we should look for these animals, yet, 

 during rainy seasons especially, our ponds, ditches, 

 and reservoirs overflow, and numbers of their micro- 

 scopic fauna are undoubtedly washed away into our 

 rivers, and so carried down to the sea. It is hardly 

 conceivable, however, that any of them could survive 

 such a sudden transition ; but we can fall back upon 

 a much more probable hypothesis. At numerous 

 places along the coast, there are either extensive 

 marshes (or fresh-water lagoons) or ditches, many of 

 respectable size, into which the adjacent cultivated 

 lands are drained, and these are frequently highly 

 suitable to Rotatorial life. Should any of these be 

 so situated as to receive incursions from the sea to a 

 limited extent, say at exceptionally high spring-tides, 

 such a condition of things would, in course of time, 

 tend to eliminate the weaker forms of life — those who 

 failed to adapt themselves to the changed circum- 

 stances — leaving the others, the fittest, to survive. 

 The following considerations are, I think, favourable 



to this view of the case. They bear only a small 

 proportion to the fresh-water forms, and it is certainly 

 remarkable, and tending somewhat to confirm my 

 theory, that with only one or two exceptions, they all 

 belong to the order Ploi'ma, sub-order Loricata. One 

 would, a priori, imagine that the Rotifera of this sub- 

 order, with their integument strengthened and pro- 

 tected by chitinous matter, would be more likely 

 than others, to survive such a change in their environ- 

 ment as must have happened on such a theory. In 

 this order are found Rotifers of the most "restless 

 energy, perfection of structure, and superior intelli- 

 gence," and whose jaws are highly developed, so that 

 in many cases they can be protruded, and used like 

 the mandibles of insects ; and in other respects they 

 are " well equipped for the energetic life, which obser- 

 vation proves them to pursue." Now looking at the 

 question in these aspects, it does certainly appear to 

 me that in all probability most, if not all the marine 

 forms of the Rotifera may be confidently looked for 

 in our fresh waters, and I trust that microscopists in 

 various parts of the country, will take up the study 

 of these charming, though fortunately ubiquitous 

 animals, and record the results of their investigation, 

 in Science-Gossip or other readily-accessible scien- 

 tific journal. 



P.S. — Since the foregoing was written, one of my corre- 

 spondents, Mr. Bryce, a member of the Hackney Micro Society, 

 has sent me a tube of Rotifers, among which were several 

 specimens of N. scapha. He had noticed the form several 

 times, and only the fact of its being found in fresh water 

 prevented him feeling sure of its identity. They were pro- 

 cured from a pond in the North of London, a circumstance 

 which, taken in conjunction with their previous capture in 

 N.E. Lancashire, proves their wide distribution, and renders 

 it very probable that a careful search will reveal them in other 

 localities. J. E. L. 



THE AXOLOTL (AXOLOTES GUTTATUS). 



By W. August Carter, 



Of the National Fish Culture Association. 



THIS remarkable animal is a species of Amphibia, 

 although it differs somewhat from others of the 

 same family. The Axolotl first became popular at 

 the time of the Mexican Conquest, when they were 

 discovered in large numbers in the waters surrounding 

 the city of Mexico. On its edible qualities being 

 tested, it was found to be nutritious and appetising, 

 and Hernandez informs us that the " flesh was con- 

 sidered as an aphrodisiac, and that it was wholesome 

 and agreeable, and tasted not unlike eel." It has 

 created considerable controversy amongst naturalists, 

 judging from the multifarious appellations by which 

 it has been known. It was referred to by Shaw as 

 the Siren pisciformis ; others regarded it as the type 

 of a new genus, while Baron Cuvier considered it to 

 be the imperfect state of a genus already known. 

 The Axolotl is possessed of both lungs and gills, the 

 latter consisting of three processes protruding from 

 each side of the neck, resembling small twigs of 

 trees. The teeth are sharp and situated in rows 



