64 ABSTRACTS OF LECTURES. 



patches on the top of the head. Many have phosphorescent 

 spots on the end and at the base of the tentacles, acting as 

 lures for their prey. 



The effect on the eyes is different in different forms. ■ In 

 some they are completely atrophied, while in others- they are 

 enormously developed as if to make the most of their 

 self-generated light. Sometimes we find eyes in the young, 

 which atrophy later, e.g. in Himantolophus and many blind 

 Crustacea. The sense of touch is well developed either 

 through the medium of long hairs, limbs, or rays. ^ There is 

 probably also some delicate sense of pressure which might be 

 utilised to make the creature aware of the approach of danger. 

 The effect on their colour is peculiar, it being in some cases 

 intensified and in others diminished. As regards size some 

 forms are dwarfed, but monsters are met with {e.g., Pycnogons 

 2 -ft. long; Isopods ii-in. long). 



Vegetable matter cannot grow in the darkness, but much 

 is carried down by rivers and currents. This furnishes food 

 to many forms, being well preserved owing to the absence 

 of bacteria. Living forms occur in greatest abundance 

 between 200 and 400 fathoms. Here are found the noted 

 Pentacrinus forests, red in their natural state. The lower one 

 goes, the less variety is met with, till in the abysses only 

 Rhizopods are supposed to exist. Migration will probably be 

 dependent on the food supply. 



The greatest regret is felt at the absence of ancient forms 

 isuch as Dipnoi, Ganoids, Lampreys, Trilobites, Graptolites, 

 and Belemnites, whereas we get such ancient forms as 

 Lingula, Amphioxus, and Limulus in shallow waters. No 

 connecting links are found which might consolidate the 

 zoological tree, as e.g., to connect Brachiopoda or Bryozoa to 

 the main groups. Either the deeps have been devoid of life 

 at geological epochs, or we need the light of further research 

 to guide our conclusions. 



