335 
CHAPTERS XV. and XVI. 
Plate XXX. — fore extremity of the mole—head of the 
ELEPHANT-FINGER-LIKE EXTREMITY OF THE PROBOSCIS-SEC¬ 
TION OF THE PROBOSCIS-BAT’S WING-BILL OF THE PARROT 
-EYES OF INSECTS-EYES OF A SPIDER. 
Fig. 1. Is the fore extremity of the mole ; a, the os humeri , is pe¬ 
culiar, not only for its shortness, but in being articulated by b y one head 
to the scapula, and by c, another to the clavicle ; it is altogether of such a 
nature as to turn the palm outwards for working. 
The foot, or we may name it the hand, has eleven bones in the carpus 
or wrist, which is two more than the carpus of man. One of which, d, 
is remarkable, and from its shape is called the falciform bone; it gives 
the shovel form to the hand. 
Fig. 2. The head of the Elephant. 
Fig. 3. and 4. The digitated extremity of the proboscis. 
Fig. 5. A transverse section of the proboscis, showing, a, a , the two 
tubes or nostrils. Between the external integuments and the tubes are 
two sets of small muscles ; an inner one running in a transverse, and an 
outward one in a longitudinal direction : b , b, the transverse faciculi of 
muscles, some of which run across the proboscis, others in a radiated, and 
some in an oblique direction : c, c, the radiated, and d, d, the oblique fi¬ 
bres approximate the skin and the tubes, without contracting the cavity of 
the latter. The others, which pass across the proboscis, contract both 
the surface of the organ, and the canals it contains ; they can, at the same 
time, elongate the whole or a part of it : c, e, the longitudinal faciculi, 
forming four large muscles, which occupy all the exterior of the organ. 
Fig. 6. The extended wings of the bat. Ostrologically considered, 
they are hands, the bony stretches of the membrane being the finger 
bones extremely elongated : a, a, the thumb, is short, and armed with a 
hooked nail, which these animals make use of to hang by, and to creep. 
The hind feet are weak, and have toes of equal length, armed also with 
hooked nails ; the membrane constituting the wing, is continued from the 
feet to the tail. 
Fig. 7. The upper mandible of the parrot , which is articulated with 
the cranium by an elastic ligament, admitting of a considerable degree 
of motion. 
Fig. 8. An eye compounded of a number of lenses. The eyes of in¬ 
sects differ widely from vertebrated animals, by being incapable of mo 
tion ; the compensation, therefore, is a greater number of eyes, or an eye 
compounded of a number of lenses. Hook computed the lenses in a 
horse-fly to amount to 7,000, and Leuwenhoek found the almost incredi¬ 
ble number of 12,000 in the dragon-fly. 
Fig. 9. The eyes of a spider , drawn from nature. The number of 
eyes in insects varies from two to sixteen. The spider here referred to 
answers the description of the garden spider, ( Epeira Diadema,) the 
eyes of which are planted on three tubercles, four on the central one, and 
two on each side of the lateral ones. 
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