38 AN HOUR AT 



sucking honey and eating pollen. In the Tipulidae, and also in 

 those flies which do not eat pollen, but live exclusively upon 

 juices — for instance, Bombylius — the two valves of the pro- 

 boscis serve no other purpose than to protect and guide the 

 sucking-tubes ; but in the flies which devour pollen, besides this 

 function, there is also that of grinding the pollen, for which they 

 have special adaptations, for the margins of the two valves at the 

 point of union are transversely dentate with fine and parallel 

 bands of chitine. Probably, the greater or less distance of these 

 bands in different species is related to the different size of the 

 pollen upon which they feed." — (Dr. Erm Miiller, of Lippstadt.) 

 I have not met in my readings with any observations on the 

 Blow-fly as a pollen-eater ; nor does it follow that because teeth 

 are present, such must always be their function ; but in the warm 

 days of autumn, when grapes are ripening, they do much injury 

 to this fruit by making holes in the " skin," and eating largely of 

 the juicy contents. 



Dermanyssus gallinse, the fowl-mite, when present in num- 

 bers, occasionally causes troublesome eruptions on human beings ; 

 and they may also become a serious nuisance to horses in 

 stables. A graphic account of the latter, too long to extract 

 here, will be found in Vol. III. of Gamgee on " Our Domes- 

 tic Animals in Health and Disease," at p. 213. 



Spine of Dog-Fish. — All the slides which I have seen named 

 " Skin of Dog-Fish" are from Scylliuin caniculum, the Smooth- 

 spotted Hound, a portion of the skin of which is shown on the 

 upper part of PI. 3, Fig. 2. The spine, from which the section 

 figured (PI. 3, Fig. i) has been taken, is from Spt?iax acanthias^ 

 the Picked (or spiked) Dog-Fish. These do not differ greatly 

 in size, though the former under favourable conditions grows to 

 be larger. The differences in colouring, however, are great. In 

 the " Smooth-Hound," the general colour of the body is pale 

 reddish on the upper parts, covered with many little spots of dark 

 reddish-brown; below it is yellowish-white. The "Picked Dog- 

 Fish " is of a bluish-grey, darker on the back, and becoming 

 almost white on the belly. It is further characterised by the 

 possession, in front of each of the two dorsal fins, of a long, 

 tapering, acute, and very hard spine (PI. 3, Fig. 3), with which, 

 unless the fish be handled with great caution, fearful wounds 

 may be inflicted. They sometimes occur on the North-Eastern 

 Coast, in large shoals, and are much disliked by the fisher- 

 men, who, it is said, used formerly to cut the livers out, and 

 then cast the poor brutes, still living, into the sea again. Those 

 who have not imbibed the stupid prejudices against them 



