242 TlMEHRI. 
prolongation of the head which is said to be brilliantly 
luminous at night, and the various forms of plant-bugs, 
several of which possess long, oar-like, hindermost legs, 
as in the passion-flower bug (Diadior). Of the wingless, 
lower insefts (Aptera) such as the lice etc., but one or 
two forms are shewn. 
Of the class Arachnida^ already mentioned, forms are 
shewn of several spiders, as for instance of the bird-eating 
spider (Mygale) — the colonial tarantula — of which the 
biting poison-fangs are very large : and of the spined spi- 
der with bifid abdomen (Acrosoma.) A fine specimen of 
the scorpion-spider (Phrynus) with the long setaceous 
modified first pair of legs is also shewn, together with 
specimens of scorpions of various sizes, one shewing the 
young, in situ, on the back, as carried during early life. 
The scorpion stings with the last segment of the body, 
injecting poison therewith, and simply grasps with the 
powerful nippers ; while the spider bites with its poison- 
fangs which are situated in front of the mouth. Of 
parasitic forms of this class, such as the mites and ticks, 
it is curious that one very minute form (Demodex) is 
found only on mankind, and inhabits the sebaceous fol- 
licles of the nose in every individual. 
Of the class Myriapoda, already mentioned, some 
large specimens of centipedes are exhibited, one being 
turned upwards to shew the position of the biting organs 
which are placed behind the mouth, continuous with a 
swollen poison-gland at the basal part Other forms of 
this class are placed by these, forms known as millipedes 
owing to their very numerous legs, of which two pairs 
are placed on each segment or ring of th% body. 
The classes of the crustaceans, inse6ls, spiders and 
