AMPHIBIANS. 59 



I have made from dissection of its Shoulder-girdle (Plate III, fig. 1, and Plate IV, fig. 1) are magni- 

 fied four diameters. The girdle is incomplete both above and below ; above, each " supra-scapula " 

 (s. sc.) is a line below the spines of the second and third vertebras below, the " epi-coracoids " 

 (e. cr.) are a line apart. The cartilaginous supra-scapula is somewhat triangular in shape, but 

 runs into a bilobate form through the concavity of the upper margin and the roundness of its 

 free angles ; the front angle projects most. The scapula (sc.) is a very delicate, flattened, pha- 

 langoid ray; it is a shaft-bone, so arrested at both ends as to make the supra-scapula appear 

 larger than it really is, whilst, below, the glenoid region is, like all the rest of the half-girdle, 

 entirely unossified. 



The whole structure on each side is continuous ; but two clefts appear, and are arrested ; 

 one, rather small, in the fundus of the glenoid cup (gl.), closed at both ends, and pear-shaped ; 

 whilst the other is a large notch, almost separating the prse-coracoid from the coraco-epi-coracoid 

 plate (p. cr., cr., e. cr.). The smaller, anterior end of the glenoid cleft answers to the generally 

 distinct nerve-passage, so well known in the coracoids of the Oviparous Vertebrata. 



This is one of the most interesting points in the morphology of the Limb-girdles : we have 

 seen the scapula completely cloven from the coracoid, and the middle brachials wedged in 

 between them in Coitus ; and now the 'first and lowest Amphibian has these two main 

 regions to a considerable extent separated by a cleft ; another instance will immediately be 

 shown, and then we see no more of this cleft until we are some way into the Class of Birds, 

 where, with the exception of the typical Ostriches, it is always present and always perfect. Once 

 out of the Bird-Class, however, and we see it no more except in the Mole ; yet in the Bird-Class 

 we always have its pelvic counterpart in the oval fenestra in the fundus of the " acetabulum," 

 partially separating the "ilium" from the "ischium" the two rays which, in the pelvis, repre- 

 sent the scapula and the coracoid. 



The cleft between the prae-coracoid and the main coracoid is imperfect proximally ; it is a 

 notch, which to a great extent separates the former knife-shaped flap of cartilage (p. cr.) from 

 the latter, which is a large, oval, convexo-concave plate, the extensive, free, thin, lower margin of 

 which does not reach the mid-line of the body ; the right and left moieties are a line apart ; this 

 distal margin of the coracoid is the "epi-coracoid" (e. cr.). Below the thickened margin of the 

 glenoid cavity the coracoid has a crescentic notch ; this is opposite the anterior cleft, so that 

 there is here a rather narrow waist to the cartilaginous plate, an isthmus scarcely two lines across 

 (Plate IV, fig. 1, p. cr., cr.). No cartilage is developed in the inner layer of the lower part of 

 the thoracic walls, such as exists in most of the Urodela ; that is to say, there is no Steruum 

 (Plate III, fig. 1). 



Example 2.- Menobranchus later alis, Harlan. 



My figures of the Shoulder-girdle of this South-American Amphibian have been made from 

 Professor Hyrtl's dry skeleton 1 of an adult male, and here I have no Sternum to speak of, 

 although I am not certain of its non-existence ; the figures are magnified two diameters 



1 I have made free use of the invaluable specimens in the Museum of the Royal College of 

 Surgeons, which were purchased of Professor Hyrtl in 1862 ; one splendid case is full of Anoura, 

 the other contains the Urodela (including the Ctecilians), and also the Reptilian Chirotes. 



