

I 

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Miscellaneous. 295 



species. From the latter it is further distinguished by the number 

 and size of the spherical bodies or saeculi. These are deficient in 

 E. japonicus and Semperi, small and scarce in E. variant. The 

 ccntrodorsal plate is small, hemispherical, and bears, in two rows, 

 thirty long slender cirri, each formed of fifteen joints, the last of 

 which is bent into a small hook. The second syzygy occurs between 

 the ninth and tenth brachial pieces, and the others at intervals of 

 four or five pieces ; the brachial pieces bear the pinnules alternately 

 to the right and left, except at the syzygy, where the piece above the 

 syzygy is the only one thus furnished. The whole length of the 

 upper surface of the arms is occupied by powerful muscular masses 

 inserted upon transverse crests traversing the whole width of the 

 plates. The brachial plates are alternately narrowed to right and 

 left ; the pieces of the pinnules are cylindrical and scarcely widened 

 at their upper extremity ; the first can move upon the brachial 

 piece, and the second upon the first ; but all the rest are nearly fixed. 

 Between the long joints of the dorsal cirri the fleshy pads are very 

 small ; and generally the cirri are stretched straight out. 



As regards locomotion, E. atlanticus is an interesting modification 

 of the Comatula type ; it cannot adhere firmly to foreign bodies, 

 and probably spreads out its arms and cirri upon the mud at the 

 bottom, where it has nothing to fear from the waves and currents ; 

 but the muscular masses of its arms would indicate that it can swim 

 well. The disk is very small in proportion to the arms, not being 

 more than 5 millini. in diameter, while the arms attain a length of 

 12eentim., and the cirri are from 15 to 20 millim. long. The 

 4 Travailleur ' obtained fifteen specimens of the species ; but most of 

 them are in bad condition. 



Notwithstanding the simplicity of their arms, the Eiuliocrini^ far 

 from being a primitive type of Comatuhe, are a considerably modi- 

 fied type. And this leads to a general remark that, if we consider 

 the principal zoological types, it appears that the various forms they 

 comprise may be referred in each type to a group of simple forms 

 from which all the others are derived, these simple forms 

 forming by gemmation colonies, the different parts of which are 

 afterwards modified and solidarized. In the type of Sponges these 

 i simple forms occur only in the group of Calcispongia? ; among the 



j - Coelenterat i tiny are the hydroid polypes ; among the Arthropoda 



the lower Crustacea depart least from the Nauplius form ; lastly the 



Annelida may be regarded as the starting-point of a group to which 



are to be referred the Brachiopoda, the iloilusca, and even the 



j Yertebrata. The representatives of these simple forms are all ex- 



l ceedingly rare and specifically few in the deeper regions of the sea, 



I while they become very numerous and varied as we approach the 



littoral zone. And, further, in each class its most modified repre- 

 sentatives are those which are most frequent at great depths. 



The Sponges are the complex, forms belonging to the Hexacti- 

 nellidsc, which began to fiourish only in the Secondary epoch ; the 

 corals are solitary corals or Aleyonaria, especially PennatulidiB, 



? 





