HARD WICKE'S SCIENCE- G OSS-IP. 



81 



antennae above the eyes, short and pointed, and 

 are scarcely seen. Between the eyes commences the 

 alimentary canal, which leads to a long oval dark 

 mass, which is supposed to contain the mouth, 

 oesophagus, &c. 



Situated on either side of the optic nerves is a pair 

 of remarkable organs which are both legs and 

 suckers, according to Dr. Baird* they are: "The 

 anterior pair or second pair of foot-jaws, and of a 

 peculiar construction. They are in the form of short 

 hollow flexible cylinders .... having a membranous 

 margin and figured all round with membranous rays 

 .... by this organisation the animal can make use 

 of them as real suckers or cupping glasses and fasten 

 itself to the fish on which it lives, and also to walk 

 with when it wishes to change its position. By con- 

 tracting these muscles it can exhaust the cavity of the 

 sucking disc, producing a vacuum, and this enables 

 it to adhere firmly to the surface upon which it is 

 placed." By Dana and Herrick they are called 

 "prehensile feet." About midway are placed two 

 pairs of long and beautifully formed legs, and further 

 below are four more pairs also plumosed and carried 

 towards the posterior. 



The abdomen consists of a pair of lobed oval 

 appendages, or perhaps egg-corpuscles, and are marked 

 with longitudinal lines about eight in number. 



At the commencement of these ovate organs are 

 two bright crimson star-shaped markings which are 

 said not to be observable in the male. Between 

 these appendages terminates the intestine canal, and 

 here is situated the anal orifice. 



This species was found on the gill of the Bass 

 \Labrax lupus). 



ON THE MITE OF THE HUMBLE BEE 

 GAMASUS. 



I SHOULD like to draw the attention of students 

 of the Arachnoida to a minute mite, which 

 I have frequently found parasitic on the Gamasi 

 infesting queen humble bees. I first noticed it, I 

 think, in the spring of 1877. I suppose it must be 

 the Hypopus (whatever that may be) of Gamasus, but 

 it differs so remarkably from all other Hypopi that 

 I have seen, or indeed from all other mites with 

 which I am acquainted, that I should like to know 

 more about it. I have found as many as seven 

 specimens on a single Gamasus. The humble bee 

 on which I first found it in 1878 was the Bombus 

 vh-ginalis of Kirby. It moves about on its host with 

 tolerable speed, giving one an idea of a pigmy tor- 

 toise ; it is covered with a shield of a brownish-yellow 

 colour, like some specimens of resin, shining, and very 

 evidently divided into an anterior or cephalic, and 

 posterior or dorsal portion. The legs are very re- 



markable, the anterior pair being rather short, broad 

 and flattened, and each front leg is provided with a 

 peculiar and large single claw, like that found on the 

 three first pairs of legs of Trichodactylus Osmice, from 

 which mite it differs also, in having the chitinous 

 shield, instead of the corrugated skin so characteristic 

 of the Sarcoptidre. The second and third pair of 

 legs are much finer, rather longer, and furnished 

 with a double claw and large pad. The hind legs 

 terminate in a few long stiff hairs, somewhat like 

 Trichodactylus, only in that creature there is but a 

 single terminal hair to each hind leg. The mouth 



Fig. 78. — Mite from Gamasus of Humble 

 bee ; X about 220. 



Fig. 79. — Front leg (a) with claw, middle feet f^and pad, and 

 hind leg (c) of Gamasus. 



' Natural History of British Entomostraca." 



Fig. 80. — Scale, xitao inch. 



parts I have not been able to make out satisfactorily, 

 but it appears to be furnished with two bristles, as in 

 Hypopus muscarum. The abdomen gives one an idea 

 of segmentation. 



The readiest way of finding them, is, first to catch 

 the early queen humble bees when they frequent 

 the catkins of the sallow : these are almost invariably 

 invested with the desired Gamasus (which is exactly 

 like G. coleoptratorum). Place one of the bees 

 under a wine-glass, or tumbler, and introduce a 

 small piece of blotting paper moistened with hydro- 

 cyanic acid. This will speedily kill the bee, but 



* Their structure is simple and fructification though various 

 in power, always sporiferous. _ 



