.•500 



province not yet known to us."' The Goniatites of this 

 fauna are associated with the millions of planktonic Stylio- 

 lina, with floated logs, and probably other pelagic organisms, 

 and the sediment in which they were embedded was such as 

 probably was not conducive to the well-being- of such 

 animals, so that their occurrence is best explained by the 

 hypothesis of flotation. 



( )f the embryology of Nautilus, and hence the whole group 

 of Tetrabranchiata. nothing is known. The Dibranchiata 

 develop directly within the egg capsule, no veliger stage 

 occurring. 



Cirripedia. — The cirripeds, or barnacles, are marine seden- 

 tary benthonic Crustacea which have degenerated much from 

 the true type of crustacean, owing no doubt to their at- 

 tached mode of life. The body is covered with calcareous 

 plates variously arranged, which fall apart after the death 

 of the animal, after which, from single pieces, it becomes 

 quite impossible to determine the species, owing to the 

 great variation of the skeletal parts (Darwin). Balanns and 

 its congeners are sessile, being attached to the rocks and 

 other solid supports along the shore, seldom venturing into 

 water < >f great depths. Some species areexposed periodically 

 at low tide for many hours at a time, some, in fact, being 

 never covered more than one or two hours at flood tide, s<> 

 high up on the shore do they attach themselves. Balanns 

 has been found at a depth of 500 fathoms, but it usually 

 lives in lesser depths. Balaam improvisus occurs also in 

 brackish water. Coronnla, diadema leads a pseudo-nektonic 

 life, attaching itself to the body of whales. Verruca ineerta, 

 a common West Indian type, occurs in the Globigerina ooze. 

 Lepas and its congeners are pedunculate, attaching them- 

 selves by a fleshy peduncle, which represents the elongated 

 headend. The majority of the Lepadidae are pelagic, lead- 

 ing a pseudo-planktonic existence, attached to floating logs, 

 pumice, or other objects. Three species of Lepas were found 

 by the "Challenger" attached to theSargassum. Somemem- 

 bers of this family descend into desp water, Scalpellum 



