1868 HUNTERIAN LECTURES 425 



forward that the line of descent of the Sauropsida clearly 

 diverged from that of the Mammalia, both starting from 

 some common ancestry. And besides this great generalis- 

 ation, the importance of which, both from a classificatory 

 and from an evolutional point of view, needs no comment, 

 there came out of the same researches numerous lesser 

 contributions to the advancement of morphological 

 knowledge, including among others an attempt, in many 

 respects successful, at a classification of birds. 



This work in connection with the reptilian ancestry 

 of birds further appears in the paleontological papers 

 published in 1869 upon the Dinosaurs (see Chap. 

 XXIII. ), and is referred to in a letter to Haeckel, p. 

 437. 



His Hunterian lectures on the Invertebrata 

 appeared this year in the Quarterly Journal of Micro- 

 scopical Science (pp. 126-129, and 191-201), and in 

 the October number of the same journal appeared 

 his famous article "On some Organisms living at 

 great depth in the North Atlantic Ocean," originally 

 delivered before the British Association at Norwich 

 in this year (1868). The sticky or viscid character 

 of the fresh mud from the bottom of the Atlantic 

 had already been noticed by Captain Dayman when 

 making soundings for the Atlantic cable. This 

 stickiness was apparently due to the presence of 

 innumerable lumps of a transparent, gelatinous 

 substance consisting of minute granules without 

 discoverable nucleus or membranous envelope, and 

 interspersed with calcareous coccoliths. After a 

 description of the structure of this substance and its 



