150 



HARDWICKE'S SCIENCE-GOSSIP. 



the mandibles; their shape is that of a two-edged 

 scalpel ; they are very sharp, and the tips are ser- 

 rated like a common saw (see md, fig. 98). When 

 not in use, they and the tongue, I, are concealed 

 beneath the upper lip, which is hollowed out under- 

 neath, so that a section would appear as a segment 

 of a circle. The natural position of the maxilla?, 

 mx, is nearly the same as in the figure, but they 

 are not so wide apart. They lie beneath the man- 

 dibles, and are furnished with a pair of palpi. One 

 edge is set with small recurved teeth, and the other 

 is fringed with fine hairs. Immediately beneath 

 the mandibles (when they are at rest) is the tongue : 

 this forms the cover of a groove in the labium. 

 The groove may be seen in the figure, and through 

 the tube so formed the blood is sucked up into the 

 throat. The lower lip, or labium, la, as is usual in 

 diptera, is the most conspicuous part of the mouth : 

 the capillary channels of the lobes are long and 

 numerous, forming a good contrast to those of a 

 bumblebee-fly's mouth, but they are few compared 

 with the number on the lip of a Tabanus. Being 

 situated on the inner sides of the lobes, their com- 

 mencement only is shown in the figure, which repre- 

 sents the labium fully extended, with its lobes par- 

 tially separated as if for suction. 



In naming the organs of the mouth we have fol- 

 lowed the nomenclature of Curtis, Westwood, and 

 Walker. P>. T. Lowne, in an article on "Mouths 

 of Insects" (Science-Gossip, page 109, 1874), 

 gives a different arraugement, calling the mandibles 

 the "great maxillae," and the maxillae "labial 

 palpi." We prefer to consider as mandibles the 

 parts we have thus named, because they are in 

 exactly the right position for these organs, viz., 

 immediately beneath the labrum, one on either side 

 of it : their structure indicates the same thing, for 

 they are without hairs or palpi. All authors agree 

 in denominating the palpi, mp, "maxillary palpi"; 

 and there seems no doubt that they are the homo- 

 logues of the palpi at the bases of the maxillae in 

 bees. Now in the mouths of the flies, Rbingia, 

 Empis, and Bombylius, these said palpi are very 

 plainly seen to be articulated to the bases of the 

 organs which Mr. Lowne calls " labial palpi " in the 

 mouth of Tabanus. Erom this we think it may be 

 reasonably inferred that they are not labial palpi, 

 but maxillae. Eurther, we believe that palpi are 

 never set with teeth [like these organs, but have 

 hairs scattered irregularly over their surface, which 

 these have not. 



We have never met with the larvae of any of the 

 Tabanidae, but it is stated by Professor Westwood 

 that they are to be found in the earth ; they are 

 long worm-like grubs with twelve segments, and 

 they have no feet. 



Gad-flies appear only in the summer, and are 

 most abundant in July. It is useless to search for 

 them except in sunny weather. The commonest 



genus, Hamatopota, is scarce on a dull day, while 

 even a cloud passing over the sun will cause Tabani 

 and Chrysopa to hide themselves — where, we have 

 never been able to discover. 



Ebank J. Allen & H. M. J. Undekhill. 



THE ELORA OF AN OLD GARDEN WALL. 



/ \LD walls are often very prolific in their vege- 

 ^ table inhabitants, especially when built of 

 the friable clayey brick so commonly used at present, 

 so that when our modern walls are old enough we 

 may look forward to an abundant and varied crop. 



My garden wall, though not very ancient, presents 

 so many forms, that a short description of it and 

 them may interest some readers of Gossip. It 

 surrounds three sides of a rectangle, the long side 

 of which is shaded by trees. Its top projects some 

 four or five inches on each side, and it is here that 

 the majority of plants are to be found. Of Phanero- 

 gams, Antirrhinum majus is conspicuous, partly 

 natural and partly growing from seed scattered. 

 Sundry tufts of Aubrietia deltoidea (also planted), 

 show their bright lilac cushions. Amongst the 

 species truly wild I find Sonchus arvensis, Senecio 

 vulgaris and S. Jacobcea, Sagina apetala, Trifolium 

 arvense, Chrysanthemum segetum, Taraxacum dens- 

 leonis, Stellaria minor, Bypochceris radicata, Poten- 

 tilla reptans, Vero7iica hederifolia, Bellis perennis, 

 Poa annua, Cerastium arvense, and Parsley. Sundry 

 fruits have also made their appearance, carried no 

 doubt by birds — strawberries, raspberries, mountain 

 ash, gooseberries, ivy, woodbine, and the garden 

 Ribes. I even met with specimens of the yew, 

 Taxus baccata, and the common sycamore, growing 

 from seeds dropped frcm neighbouring trees. 



Of the Cryptogamia, mosses and lichens, espe- 

 cially the former, are pretty numerous, including 

 the following species : Tortula muralis, Grimmia 

 pulvinata, Bryum argentenm, B. capillare, Bypnum 

 velutinum, H. rutabulum, B. cuspidatum, and possibly 

 one or two others. Of the lichens the most abun- 

 dant aie Borrera stellans, Parmelia saxatilis, and 

 Cladonia pyxidata. This list includes twenly-seveu 

 flowering plants, seven mosses, and three lichens ; 

 one fern only has made its appearance, Scolopendrium 

 vulgare. Algae and fungi are conspicuous by their 

 absence, the latter being only represented by some 

 doubtful splucraceous forms, at least at this time of 

 year. In summer sundry parasitic species sometimes 

 make their appearance. This list is the result of a 

 very cursory examination ; a more detailed one 

 would probably reveal other forms. Unfortunately 

 I am no entomologist, or I doubt not the fauna of 

 our garden wall would be as numerous and interesting 

 as its flora, or more so. 



G. D. P. M. 



