The life-history of British lizards : and their local distribution in the British Isles . sents itself in thisconnection is this. Seeing that in most animalspossessed of long tails the muscles are attached fromone vertebra to another, allowing of a certain amountof intervertebral movement, but keeping the tail, as awhole, attached to the body even if a fracture ofa vertebra occurs, what special muscular arrangementexists in those hzards which drop their tails whenthis accident happens ? Secondly, even if by someanatomical arrangement the muscles do not keep thetail attached to the body, how is
The life-history of British lizards : and their local distribution in the British Isles . sents itself in thisconnection is this. Seeing that in most animalspossessed of long tails the muscles are attached fromone vertebra to another, allowing of a certain amountof intervertebral movement, but keeping the tail, as awhole, attached to the body even if a fracture ofa vertebra occurs, what special muscular arrangementexists in those hzards which drop their tails whenthis accident happens ? Secondly, even if by someanatomical arrangement the muscles do not keep thetail attached to the body, how is it that the skin orintegument always breaks all round the circumferenceof the tail exactly over the point of the fracturedvertebrae ? (The species of lizards first used to investigatethese points were Aiiguis fragilis, the slow-worm, andLacerta viridis, the green lizard, of the Continent andChannel Islands.) 1. Anguis fragilis, the Slow-worm. Selecting a specimen from my collection, I proceededto carefully break off a portion of the tail. It was SLOW-AVORM : ALMOST COMPLETE PORTION OF TAIL OF SLOW-WORM : TWO INCOMPLETEFRACTURES. {Facingp. io6. FRAGILITY OF THE TAIL IN LIZARDS 107 at once evident that while the integument rupturedreadily round the circumference of the lower half (theventral half) of the tail at the point of fracture, it didnot do so nearly so easily on the dorsal aspect. Infact, some degree of force was necessary to completethe division of the skin all round. But by bendingthe two halves of the tail, as one would bend a stickacross the knees, the fracture was completed. Thestructures thus separated in the following order:— First, the ventral integument; Then the ventral muscles ; Then the lateral integument and muscles oneach side; Then the dorsal muscles; Lastly, the dorsal indicates the degree of ease with which theparts separated, the ventral aspect rupturing mosteasily, the dorsal remaining intact the longest. Thefirst thing tha
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Keywords: ., bookcentury1900, bookdecade1900, booksubject, booksubjectreptiles
