532 TRANSACTIONS OF SECTION D. 
logical features, has formed the subject of many discourses as to its position 
in the Arthropod classification. 
The important and essential characteristics were reviewed and the views 
of various authors discussed as to its relationship with the Myriapoda and 
Insecta. The reader deplored the use of the term Myriapoda to represent what 
was not a class but a convenient assemblage of ‘ many-legged’ arthropods, and 
restricted his remarks to the one so-called Myriapod Order, Chilopoda, or Centi- 
pedes, highly organised Arthropods coming near to the Znsecta. He considered 
that whilst the Protura had affinities with the Chilopoda, especially Lithobius, 
in the larger number of body-segments and the position of the genital opening, 
the weight of evidence lay in favour of modifying the classification of the insect, 
dividing it into two sub-classes, the one to include Protura, and the other to 
include all other Orders of insects. 
4. The Early Evolution of the Amphibia. By D. M. S. Watson. 
In the Lower Carboniferous and Productive Coal Measures of England all 
the known large Amphibia agree in the following features : The main articulation 
of the skull with the vertebral column is by a single large concave basioccipital 
condyle, the pterygoids articulate with small ventrally directed basipterygoid pro- 
cesses of the basisphenoid, the parasphenoid is small, and the interpterygoid 
vacuities practically absent. The vertebral column is throughout embolomerous. 
In two types the exoccipitals articulate with the vertebral column, in one case by 
very small separate facets, in the other by combining with the much larger basi- 
occipital to form a tripartite condyle. Inthe large Permian Amphibia the articu- 
lation of the skull is by two large exoccipital condyles, but the basioccipital is still 
still of reasonable size, and may perhaps in some cases articulate with the atlas. 
The pterygoids articulate with much exaggerated and in the main laterally 
directed basipterygoid processes formed by the otherwise much-reduced 
basiphenoid, which is supported by the enlarged parasphenoid. The inter- 
pterygoid vacuities are much enlarged. The vertebral column is rachitomous— 
a condition which is derived from the embolomerous by the squeezing out of the 
lower part of the pleurocentra and the upper part of the hypocentra; the 
hypocentra pleuralia represent the remnants of the suppressed upper part of the 
bone. 
Further change in the same direction leads to the structure found in the 
Triassic types, where the basioccipital and basisphenoid are extremely reduced, 
and the pterygoids are supported by the huge parasphenoid with which they are 
sometimes united by suture. The interpterygoid varieties are very large. 
In the vertebral column the intercentra seem to have been enlarged at the 
expense of the pleurocentra forming the so-called centrum of the stereospondylus 
vertebra, but much further work is necessary on this point. 
In conclusion, taken as a whole the rachitomous Amphibia are intermediate 
in their structure, as they are in time, between the embolomerous and the 
stereospondylous types, and it seems that each of the three groups is to be 
regarded as ancestral to that which follows it. 
The almost absolute identity of the skulls of Pferoplax, an embolomerous 
amphibian of Carboniferous type, and Seymouvia, which has the most primitive 
skull of any known reptile, seems to show definitely that the reptiles did arrive 
from that group of Amphibia, presumably in early Carboniferous or Upper 
Devonian time. 
The suggestion may be made that the development of the bicondylar articula- 
tion of the skull of Amphibia is to be correlated with increasing depression of 
the skull, and is a characteristic amphibian feature. 
5. Note on the Skull and Teeth of Tursiops. 
By Professor R. J. Anperson, M.D., F.L.S. 
The teeth present some characters which are not usually found in Cetacea. 
The number of teeth amounted to 90, but several were absent, owing to injury 
of the lower jaw. Of the teeth now under observation, three are but little worn 
—each is 3'5 cms. in length—and were perhaps about 4 cms. when unworn. The 
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