GIGAKTOPHIS GAESTINI. 307 



Genus GIGANTOPHIS, Andrews. 

 [Geol. Mag. [4] vol. viii. (1901) p. 438.] 



This genus includes very large snakes, distinguished from the recent Pythons in 

 having vertebrae in which the neural spine is less developed and the articular surfaces 

 of the zygosphene and prezygapophyses and of the zygantrum and the postzygapophyses 

 respectively are nearly parallel with one another. 



Gigantophis garstini, Andrews. 



[Plate XXVI. figs. 1-3.J 

 1901. Gigantophis garstini, C. W. Andrews, Geol. Mag. [4] vol. viii. p. 438, fig. 1. 



Type Specimen. — A series of about twenty associated vertebrae, with some fragments 

 of ribs (PI. XXVI. fig. 1) ; Geological Museum, Cairo. 



The type and only known species, distinguished by its large size, it having attained 

 a length of about thirty feet (rather more than 9 metres), if the proportions of the 

 vertebrae compared with the length of the body were as in Python molurus. 



Form. & Log. — Qasr-el-Sagha beds (Middle Eocene) : north of Birket-el-Qurun. 



Remains of this large Ophidian are very common in the Qasr-el-Sagha beds, 

 occurring usually as isolated and much-weathered vertebrae. In the type specimen 

 the vertebrae remain united in groups, one of which is figured on PL XXVI. fig. 1. 

 These vertebrae are closely similar to those of Python, the chief differences being that 

 the neural spine is less developed, being confined to the posterior part of the arch, 

 and that the planes of the articular surfaces of the zygosphene and prezygapophyses 

 and of the zygantrum and postzygapophyses respectively are more nearly parallel 

 Avith one another. 



In the procoelous centrum the transverse diameter of the anterior cup is slightly 

 longer than the vertical one ; the posterior ball is of corresponding form, and looks a 

 little upwards instead of directly backwards ; on the posterior half of the ventral surface 

 there is a low, blunt, hypapophysial ridge [hyp.]. The neural arch is extremely 

 massive, and on its posterior half it bears a small, stout, neural spine [n.sp.). The 

 anterior zygapophyses (a.z.) form strong prominences, continuous below with the 

 transverse processes ; their articular surfaces are roughly triangular in outline, and 

 look rather more inwards than in Python, in which they are nearly horizontal. The 

 zygosphene [zs.) is a greatly thickened prominence, the articular facets of which look 

 outwards and downwards and are nearly parallel with the surfaces of the anterior 



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