288 NOTES. 



canal presents an oesophagus, a gizzard, a glandular stomach, and 

 an intestine," while the latter animals have only " a radiated sac with 

 one aperture." Yet, does any one, for that reason, think of placing 

 the polypes above the star-fishes ? It cannot be pretended that these 

 and many similar facts are not well known, for they are in every 

 tolerable manual of physiology. Yet, in direct contradiction of 

 them, the opponents of the theory of development persist in assert- 

 ing that the first fishes in the geological record are the highest in 

 the book of the zoologist ! 



For further explanations on this point, the reader is referred to 

 the chapter entitled The Affinities and Geographical Distribution of 

 Organisms. 



The early occurrence of fishes, with a peculiarity of structure 

 allying them to the reptilian class, while fishes possessing no rep- 

 tilian affinities come into existence, in large numbers, long after- 

 wards, is sometimes brought forward as one of the proofs that the 

 fish class commenced with its highest forms. In strict fact, the 

 Sauroids are not the first fish: they were preceded in the Upper 

 Silurian formation by Placoids, and in the chart of M. Agassiz 

 (copied in Jameson's Journal, Oct. 1844), they come after another 

 large family of their own order, the Lepidoids. With regard to the 

 subsequent rise of non-reptilian fishes, the reader will see some 

 suggestions in the chapters on The Affinities and Geographical 

 Distribution of Organisms. 



An objection of more recent occurrence arises from certain 

 reptilian remains found in strata, supposed to be of the New Red 

 Sandstone, in South Africa. One portion of these remains indicates 

 an animal more huge than the crocodile. Another goes to form a 

 new lacertian genus, combining characters of the lizard, crocodile, 

 and tortoise, and to which Mr. Owen has given the name ofDicynodon, 

 on account of two canine tusks which projected downwards with an 

 outward curve from the upper jaw of the animal, the rest of the 

 mouth being horny and toothless. These tusks, both as to their form 

 and internal structure, are regarded as of mammalian character. 



Here, too, it is said by the opponents of the development theory, 

 we find traits of superior organization in the earliest animals of a 

 particular class. 



That these Bidentals, as Mr. Owen more comprehensively calls 

 them, are amongst the earliest reptiles, is by no means ascertained ; 

 for the situation of the strata, in which they have been found, is 

 unfixed. But, admitting that they were of early occurrence among 

 reptiles, their exhibiting an approximation to mammalian dentition 

 cannot truly be regarded as a proof of their being high in their 

 class. We know well that a superior development of one organ, 

 more especially an external one, tells nothing to that effect. The 

 echinus, a member of the echinodermata, is furnished with teeth, 

 while, in the superior family of holothuria, they are reduced to rudi- 

 ments. Miiller detected in tbe scorpion most of the parts which 

 enter into the eye of the vertebrated animal, as well as a similarity 



