90 QUARTERLY CHRONICLE OF MICROSCOPICAL SCIENCE, 
Skeleton and Muscles.—Schenk, in the text-book above 
noticed, states that in sections of early human embryos (long) 
he finds evidence of the existence of more than five fingers. 
Carl Vogt, in reference to the occasional occurrence of six- 
fingered men, has maintained that the early ancestors of man 
must have possessed more than five digits. ‘This, however, 
must have been, we may remark, in ancestors of an earlier 
grade than the first Pentadactyla, a group which includes all 
the known Vertebrata, with the exception of the extinct 
Enaliosauria and the Fishes, Lampreys and Lancelet. 
Frenkel (Jenaische Zeitschrift 1873, pp. 891-457) discusses 
the development of the Mammalian sacrum. Gegenbaur 
has shown that in Birds and Reptiles, of the numerous verte- 
bree taking part in the formation of the sacrum, only two are 
provided with sacral ribs and united to the iliac bones. 
‘These, then, are the ¢rwe sacral vertebre, the rest are pseudo- 
sacral vertebre. Frenkel studied the sacrum of Man, Dog, 
Cat, Guinea-pig, Rabbit. He finds in Man, that the three 
anterior sacral vertebre alone take part in the sacro-iliac 
synchondrosis, and possess true sacral ribs. They have each 
five centres of ossification; the two lower. sacral vertebree 
have only three each. 
The Primitive Vertebrate Limb or Archipterygium.—Gegen- 
baur in the ‘ Jenaische Zeitschrift,’ vol. vii, in consequence 
of the exceedingly important discoveries of Giinther as to the 
structure of the fin-skeleton in the new Australian Dip- 
neuston—Ceratodus Forsteri—modified to some extent his 
previous teaching as to the nature of the primitive vertebrate 
limb. The Archipterygium is, according to him, closely 
represented by the fin of Ceratodus with its axial segmented 
cartilaginous rod provided on each side (lateral or outer and 
medial or inner) with diverging radial pieces. In Proto- 
pterus the medial series of radials are suppressed, in Lepi- 
dosiren both medial and lateral series. In Sharks the lateral 
radials are enormously developed, the two proximal ones of 
the series being transferred from attachment to the Archi- 
pterygial basal piece to direct articulation with the shoulder- 
girdle, and constituting there the Mesopterygium and Pro- 
pterygium, whilst the original basal piece is the Me- 
tapterygium: In the paper referred to on the Archi- 
pterygium Gegenbaur gives evidence of the existence in Sharks 
of medial radialia, developed it is true to but a small extent, 
but still present. In the ‘ Jenaische Zeitschrift,’ vol. vin, 
part 2, 1874, A. Bunge, of Dorpat, gives additional evidence 
from various Selachian genera of the double series of radials 
with which the Archipterygium is typically furnished. 
