HA RDWl CKE 'S S CIENCE - G SSIF. 



15 



MICROSCOPY. 



Amphitetras Antediluviana. — In the number 

 of Science-Gossip for December, 1867 (vol. iii. 

 p. 271), Mr. F. Kitton contributed a valuable paper 

 on the genus Amphitetras, and amongst others, de- 

 scribed this species, together with two varieties of it : 

 /3. With sides deeply incurved, and angles much pro- 

 duced ; and y, with five incurved sides. Of the 

 latter (which is figi.u-ed) Mr. Kitton remarks : " This 

 variety appears to be rare, as I know of only one 

 locality in which it has been found, viz., Hayling 

 Island, Hants, in which it was rare." I have seen 

 no record of the occurrence of this beautiful diatom 

 elsewhere, and therefore have much pleasure in 

 adding a second locality, also in Hampshire, viz., 

 Lymington. Last week I collected material from 

 two places, the shore of the Solent below South 

 Baddesley, exactly opposite Yarmouth ; and the bank 

 of the river 'facing Lymington. The first gathering 

 yielded Ainphi. antediluviana, var. /3, in great abun- 

 dance, but without the typical form ; the second pro- 

 duced var. /3 in less numbers, sparingly intermixed 

 with var. y. Should Mr. Kitton care to see a speci- 

 men, I shall be happy to send him a slide on receiv- 

 ing a line from him. I would be glad to know 

 whether this beautiful pentagonal form has been 

 found in other counties.—^. D. Marquand, Brock- 

 inhitrst. 



Waterproof Cement. — I should like to know 

 the formula for a cement impervious to water, and 

 which neither peels off nor cracks. The cement is 

 required for the purpose of spinning rings on dry test- 

 slides, so that immersion-lenses may be used without 

 the water running in. The cements used by English 

 mounters and MoUer are neither impermeable nor 

 durable. Perhaps I may get the required informa- 

 tion through the kindness of some of your readers 

 who have employed such a cement, and tested its 

 qualities. — A. S. G. 



A Word about the "Pygidium." — That old 

 well-known "test," the pygidium of the flea, is one 

 of the first objects a young microscopist desires to 

 possess, and a veiy curious apparatus it is. I shall 

 be thankful to any one learned in such matters who 

 will tell me what is supposed to be its use to its pro- 

 prietor. I cannot find it mentioned in any woi-k on 

 insects in my possession. But the flea is not the 

 only possessor of a pygidium, though it certainly is 

 A I in that line ; nor is it always single, or to be 

 looked for in the same position. Generally it is to 

 be found in pairs at the extremity of the abdomen ; 

 but not always, for in the Ixodes of the tiger and 

 Indian bullock we find two on the underside of the 

 abdomen, nearer the upper than the lower end. The 

 Chrysopa perea and vulgaris have pygidia in the usual 

 locality; and, I believe, several other insects have 



the same, but I cannot recall their names. Perhaps 

 the most uncommon pygidia are those of the Agrion 

 pidchclliun, a very interesting insect in many points. 

 Like all dragon-flies, it is a voracious feeder, and de- 

 vours all it can catch in the insect line daily. It 

 possesses a powerful set of jaws for breaking up its 

 prey, and gastric teeth, well suited for "grinding the 

 bones to make its bread," like the giant of our 

 nursery days, save that he preferred Englishmen to 

 English insects. The ovipositor has a formidable set 

 of jaws, something like those of the Sirex, and its 

 pygidia are large and mammiform, quite at the ex- 

 tremity of the abdomen. Its wings are also worth 

 studying. In short, I know no insect possessing 

 more points of interest, and strongly recommend it to 

 the notice of those who take a pleasure in such things. 

 If asked where it is to be had, I may say that it is not 

 in any list of objects that I have seen. My specimens 

 oi Agrion pulchelluni and Chrysopa are by Mr. Enoch, 

 of 30, Russell Road, Seven Sisters' Road, N., who 

 has, I believe, a good supply of both. But, if the 

 want be made known, others possibly may be found 

 able to supply them. — John Bramhall. 



The Viviparous Blenny. — This well-known 

 fish, rejoicing in such other popular names as the 

 " Greenbone," " Eel-pout," &c. [Zoarces vivipancs), 

 retains its ova until they are hatched within the body 

 of the female, and therefore come into the world 

 alive. I obtained several females lately, full of 

 young. Although the female had just died, I cut 

 open the belly, and liberated some hundreds of young. 

 One of the latter, placed under the microscope, and 

 viewed with a quarter-inch objective, showed the 

 circulation of blood in the transparent tail-end of the 

 body for more than five hours afterwards. It is the 

 best object I know of for showing blood-circulation, 

 the shape of the corpuscles being often clearly de- 

 fined. — y. E. Taylor. 



Parasites on Midge. — Is it generally known 

 that the small midge Psyehoda is infested with para- 

 sites ? I have often found this midge with from one 

 to four of what, for a better name, I must term lice, 

 small creatures somewhat resembling cheese-mites, 

 but of a yellow or light cinnamon colour. They cling 

 to the abdomen, ranged closely together, with their 

 heads towards the heart of the midge. On being 

 disturbed, they run away very quickly. I have suc- 

 ceeded in mounting on a slide one good specimen 

 along with the fly. I have also noticed in pressing 

 one of these live midges under a glass cover with a 

 view to mounting, on one occasion one, and on 

 another occasion two, minute worms expelled from 

 its body. Under the microscope their appearance and 

 motion closely resembled thread-worms [Asearides). 

 The vitality of these parasites was very extraordi- 

 nary. They lived more than a quarter of an hour on 

 a glass slide, kept moist with spirits of turpentine ; 

 and under dammar (dissolved in benzole) they con- 



