362 
vertebre. It is only by a loose figure of speech that we speak of 
the constituents as fused, coalesced or united. The word “connate” 
suggested by OwEn (32, p. 96) commends itself for use in such cases. 
Both KOELLIKER (26, p. 238) and GEGENBAUR (17, p. 34) have 
remarked how the cartilage of the vertebral body of this first segment 
fails to completely surround the diminished notochord, and that the 
development is consequently not so perfectly perichordal as is the case 
with the first vertebra of many epichordal types, e. g. Pelobates 
fuscus and P. cultripes. The cartilage of the first vertebral body 
remains for a long time continuous with the cartilage of the basis 
cranii, and it is only towards the end of the metamorphosis that the 
occipital articulation is developed. The diapophyses are but slightly 
shorter than those of the following vertebra, and terminate peripherally 
in slightly expanded cartilages. The diapophyses which extend farthest 
outwards from the median line are those of the second segment 
(vertebra 3). The succeeding diapophyses get gradually shorter as 
far as the eighth vertebra. 
Autogenous ribs have long been known in the genera of the 
family Discoglossidae, but their presence has not been recorded in 
any other Anura. In Pelobates the contour of the transverse 
process of the third vertebra is such as to suggest the fusion of a 
rib and a short diapophysis, but an appeal to embryology does not 
yield the confirmation to be expected, for at no stage in development 
are independent ribs to be detected. Neither have rib rudiments been 
described in any works treating of the development of the vertebral 
column of Anura. ScHWEGMANN, it is true, speaks of pleurapophyses 
in the larve of Rana temporaria, but he uses the term as 
synonymous with transverse processes (38, p. 649—650). It is of 
exceptional interest, therefore, to find that in both Pipa and Xeno- 
pus distinct ribs are present in the larva, and that it is only during 
the later stages of metamorphosis that their identity becomes lost. 
In the adults of both Xenopus and Pipa the transverse processes 
of the third and fourth vertebre are very long and backwardly, as 
well as outwardly directed, and those of the fourth vertebra bear large 
terminal plates of cartilage projecting backwards so as nearly to touch 
the anterior end of the ilium. These terminal cartilages in Pipa 
have been regarded as rudimentary ribs by MEcKEL (28, p. 3885—386), 
Ducks (12, p. 58), Srannrus (39, p. 131), Owen (32, p. 50) and 
Horrmann (21, p. 56 and Taf. 19, Fig. 13), but an appeal to any 
young Pipa before it quits the back of the mother will show that 
the expanded plates of cartilage are merely the terminal appendages 
of the true ribs (see Figs. 1 and 2). 
