244 



HARJDWICKE'S SCIENCE-GOSSIP. 



were, as I have before stated, very evidently newly- 

 emerged from the chrysalis. 



It is ridiculous to suppose that butterflies could 

 possibly travel long distances to particular localities, 

 against the wind, through showers and comparative 

 gloom. Moreover, after this trial, if completed, they 

 would surely be tattered specimens. Thirdly, it is a 

 sheer impossibility for a butterfly, presented to the 

 world about 8 a.m., in France, to travel thence to 

 Cardiganshire so as to arrive at 10 or II o'clock the 

 same morning. 



Passing on to consider the question of a few hiber- 

 nated specimens immigrating to form the nucleus of 

 a large autumn brood, I must candidly admit that 

 to me there does not seem an atom of probability in 

 this story. Hibernated Edusas are rare. In localities 

 where the autumn broods appeared in greatest num- 

 bers, I had not seen a single hibernated insect in the 

 previous spring. And if these were to be the parents 

 of the autumn flies, they must have frequented the 

 same localities as those in which their progeny were 

 to emerge. 



I cannot imagine, even if such a thing did happen, 

 how these hibernated Edusa: should be so widely and 

 evenly distributed and at the same time possess 

 sufficient strength to become the parents of such a 

 healthy brood as naturalists have noticed almost 

 everywhere. Supposing, by some miracle, that 

 swarms were taken on the breast of some strong 

 south wind, and wafted over the seas from the main- 

 land, what myriads there must have been to popu- 

 late nearly the whole country with their offspring in 

 the following autumn ! and these myriads hibernated 

 specimens ! I cannot believe that such swarms 

 would appear in spring. Even if they did appear, 

 would they be immediately taken by Zephyrus, and 

 wafted and dispersed in thousands here and there, 

 over an area of hundreds of miles ? 



My own idea (it is only an idea) is that the appear- 

 ance of such numbers of Colias Edusa at intervals 

 is an accidental occurrence, dependent upon certain 

 other accidents in environment — food-plants, weather, 

 certain winds and degrees of temperature, absence of 

 peculiar parasites, etc., which perchance, affecting 

 only the first, second, or third stages, have resulted 

 in the superabundance this year, of the male imago. 



Still the question is extremely interesting to pursue 

 until a complete explanation is arrived at. 



In 1887, the insect was abundant near Cork. A 

 friend of mine brought over a number of good speci- 

 mens, all but one of which were males. By-the-bye, 

 the insects which I have in my cabinet are all rather 

 large and brightly coloured — not so dark as others 

 from farther south. For myself, I shall be very 

 anxious to note the approach (and circumstances con- 

 nected therewith) of next August, and Colias Edusa. 

 Three Brown Hairstreaks ( Theda betake) that I have 

 captured in this neighbourhood were all females. 

 T. Alfred W. Rees, F.R.M.S. 



POND LIFE STUDIES. 



No. II. — Daphnia pulex. 



By H. Durrant. 



THE subject of this paper is one that is familiar, 

 I should say, to every nature-lover. The 

 comparatively large size of Daphnia renders it ex- 

 tremely liable to figure frequently in the trough of 

 those whose friends like to see "something alive" 

 under the microscope. As to its haunts I need say 

 nothing, I am convinced ; and its plenitude — well it 

 is this genus which one often notices in such 

 numbers that the water is coloured to a deep red by 

 their presence. General : Here is its position in the 

 animal world : — Sub-kingdom, Annulosa ; Class, 

 Crustacea ; Division, Entomostraca ; Legion, Bran- 

 chiopoda ; Order, Cladocera ; Family, Daphniadce ; 

 Genus, Daphnia; Species, pulex. These little 

 creatures have only a single eye, as in Cyclops, and 

 are enclosed between, and protected by, a shell 

 (doubled over, according to Turine) without any 

 indication of a hinge. The head projects beyond 

 this shell in the form of a prominent beak. There 

 are four to six pairs of feet, terminated in a pectinate 

 manner. With the exception of the two first, they 

 are provided with branchial lamina?. Antenna?, two ; 

 largish ; arm-like, divided into several branches, 

 placed on a peduncle, the fringed filaments always pro- 

 jecting and serving as oars. Eggs situated on back. 

 Body terminated by a kind of claw with two filaments 

 of extreme fineness at the end. Latreille gives the 

 following sub-genera : — Polyphemus, Miiller ; Daph- 

 nia, Muller ; Zj>nceus,'Mul\er : (Chilodorus, Leach ?). 

 The division in Baird's " Entomostraca " includes 

 the following : — 



Daphniid/E. 



Daphnia. 



Moina. 



Bosmina. 



Sida. 



Macrothrix. 



Daphnella. 



The two other families I leave out, as having no 

 bearing on our present subject. Of the Daphnia, 

 Schjefferi is the largest, being about one-fifth of an 

 inch in length by two lines broad. 



Specific : Daphnia pulex, Latreille ; Monoculus 

 pulex, Linnaeus ; Pulex aquaticus arliorescens, Swam- 

 merdam ; Le perroquet d'eau, Geoffroy ; Daphnia 

 pennata, Muller ; D. ramosa, Koch ; Pou aquatitjue, 

 Joblot ; Vermes minimi rubri, Bennett ; Puceron 

 branchu,Tizmb\ey ; Animaletti aquatici, Kedi. This 

 is the common water-flea. Head rounded above and 

 produced into a beak. Antenna? ; superior under 

 the beak ; very small ; inferior large. Anterior 

 branch four-jointed, the first joint being very short ; 

 a filament arises from end of the third ; fourth joint 

 terminated in a like manner by three filaments. Fila- 

 ments plumose. Valves of the carapace oval ; dorsal 

 margin not serrated ; terminated by a longish serrated 



