REMARKABLE TORTOISE, TESTUDO LOVERIDGII. 499 



bridge between them) and second costal plates, thus separating 

 the first lateral fenestra from tlie first and second median 

 fenestra* on each side ; the broadly curved anterior edges form 

 an uninterrupted suture with part of nuchal, whole of first and 

 second, and inner coi'ner of third marginal plates in most cases, 

 bi^t sometimes the distal portion is undeveloped, and theiefore 

 less wing-like, or cleft, or perforated beneath the shield-sutures 

 (vide text-fig. 9). 



Text-fio'ure 9. 



Left first costal plate from beneath, showing perforation beneath vertebro-costal 

 shield-suture ; distal end incompletely developed, and cleft. (Nat. size.) 



Fenestrse between first and second costal plates are from front 

 to back as long as one marginal, from side to side two or three 

 times this length. 



Second costal plates (cp. 2) slender, feebly developed, widely 

 separated from the neural ; anterior and posterior heads forming 

 narrow sutures with first and third costal plates beneath costo- 

 vertebral shield-sutures, main arms supporting transverse costal 

 shield-suture, and uniting distalJy with the fourth marginal plate. 

 Length of each (measured from end to end) three times breadth 

 (measured from front to back) ; median head forming a short- 

 pointed process directed inwards, but widely sepaiated from the 

 vestigial second neural plate. The X-ray plates of the types 

 show that these processes are sometimes connected with the 

 vestigial rib-heads by the ligament-like periosteal tissue of the 

 absorbed rib. 



Third costal plates (cp. 3) extremely slender, rib-like, and feebly 

 developed. Main arms half or less than half breadth of those of 

 second, from which they are separated by a fenestra about half 

 as broad as those preceding. Each has three heads, each one of 

 which is twice as broad as the main arm, the median uniting by 

 suture with the third neural plate, thus forming a bridge between 

 second and third median fenesti'se on each side ; anterior and 

 posterior heads directed obliquely outwards, similarly united with 

 the corresponding heads of second and third costal plates, which 

 are directed obliquely inwards beneath the costo-vertebral shield - 

 sutures. 



In the specimen in Avhich development has been arrested at a 

 Proc. Zool. Soc— 1922, No. XXXV. 35 



