IOO 



HARDWICKKS SCIENCE-GOSSIP. 



The remarkable thing about many of these fossils, as 

 a rule, was that they were "missing links." Many 

 of them came to fill in the gaps which existed in the 

 living scale of animal and vegetable life. Thus the 

 Dipnoids, which are so abundant in the Old Red 

 sandstone or Devonian formation, are a link between 

 the fishes and the amphibians. The Dinotheria, 

 reptiles which existed during the Oolitic period, and 

 many of which attained a huge size in America and 

 Europe, were remarkable for their bird-like affinities. 

 This bird-like relationship, which is now only repre- 

 sented in existing reptiles by a few useless bones, was 

 then still further intensified by the discovery of a 

 feathered reptile, or a reptile which could fly. The 

 first mammals, or warm-blooded terrestrial animals, 

 that appeared early in the Secondary period, were 

 of the same kind as those which now exist on the 

 Australian Continent. Only one or two species were 

 known to have existed at the beginning of the 

 Secondary period, but by the close of the period 

 about a score have since been discovered adapted to 

 various conditions of life. It was not till the Tertiary 

 period that true placental mammals — animals which 

 bring forth their young alive — are known to have 

 existed. About this time the grasses, the earliest of 

 herbaceous flowering plants introduced on the face 

 of the earth, had become "social," or acquired the 

 habit of growing together, and this seems to have 

 affected the mammalian life of the world in no small 

 degree. The first known placental mammals were 

 herbivorous. Their types were very generalised, that 

 is to say, they possessed characters which have since 

 then been split up into half-a-dozen genera, and 

 perhaps into several families. Speaking of the 

 generalisation of life, Dr. Taylor said it was the same 

 with the earliest insects that appeared in the world. 

 They belonged to generalised types, or, in other 

 words, possessed characters which were now sever- 

 ally distributed to leading families of insects. 



The lecturer then contrasted the on- 

 ward progress of the mammalian life 

 during the Tertiary period, illustrating 

 his remarks by specimens taken from the 

 Museum collection, which he said occu- 

 pied no small or unimportant space in 

 the demonstration of the progressive life 

 of the world. After having pointed out 

 our increased knowledge of the fossil vege- 

 table life, due largely to microscopic inves- 

 tigation of fossil vegetable tissues, the 

 lecturer concluded amid great applause. 



Volvox GLOBATOR. — I read in Pritchard's " Natu- 

 ral History of Animalcules," 1834, that infusions of 

 hemp-seed and Tremella are said to abound with 

 specimens of Volvox globator. What is Tremella ? 

 And is the assertion supported by experimental fact ? 

 I have tried hemp-seed and failed. — R. II. Nisbett 

 Brown. 



NOTES ON TURBELLARIA. 



PERHAPS a word from this side of the Atlantic, 

 may not be uninteresting to your readers. Not 

 far from my house is a half-stagnant pool covered 



H 



j!!Nltii«:'r«, 



ji 



> 1. |i i' 



Fig. 39. — Worm as usually 

 seen crawling. 



Fig. 40.— Worm under compres- 

 sion, showing proboscis (D) 

 in position. 



by lemna and shaded by alders all the summer long. 

 In this pool, a "happy hunting ground" of mine, I 

 have found in numbers quite abundant, a Turbellarian 



Fig. 41. — Proboscis exserted. 



worm, which until recently I supposed to be Planaria 

 torva. While manoeuvring one of them, trying to 

 free from it an external parasite, for the better study 

 of the parasite, I chanced to crush the worm. 

 Immediately there issued from the body a number of 

 tube-like forms, each of which moved about the 

 slide, elongating and contracting itself, and keeping 



