ANNELIDS OF THE OLDER ROCKS. 



699 



Having previously alluded to certain convoluted forms in the Cambrian Rocks of Llainpeter, p. 363, 

 which were not then referred to any known organized body, I have now to acquaint my readers that 

 having submitted them to Mr. W. MacLeay, he has pronounced them to have been "sea worms," 

 and has favoured me with the following description, prefaced by a short general view of their place 

 in the animal kingdom. The Serpulites longissimus, a well-known fossil of the Upper Ludlow 

 Rocks (see pp. 200 and 608.), with the nature of which we were previously unacquainted, is thus 

 assigned to its proper place among the Annelida. See p. 699. Mr. MacLeay has permitted me to 

 affix specific names to the forms in the Cambrian Rocks described by him \ viz. 

 Nereites Cambrensis, so named from the rocks in which it occurs. 



Sedgwickii, from the geologist who illustrates the Cambrian System. 



Myrianites Macleayii, after the naturalist who describes these fossils. 

 Nemertites Ollivantii, after their discoverer. (See p. 363 and Table p. 714.) 



Loc. Llampeter, Caermarthenshire. In the schistose building- stone of that place, in which 

 they were found by the Rev. A. Ollivant, Professor of Llampeter College. 



Note on the Annelida. By W. S. MacLeay, M.A. F.L.S. &c. 



These animals differ from true Annulosa in being hermaphrodite, and in general red-blooded 1 . 

 They are soft vermiform animals of an articulated structure, and which form the immediate con- 

 nexion between such Vertebrata as Amphioxus and Myxine, and such Annulosa as Porocephalus 

 and other white-blooded Vermes, which have the sexes distinct. 



I divide the Annelida as follows : 



ANNELIDA. 



Noemal Group. 



Animals free, having a distinct head provided 



with either eyes or antennae or both. 

 Animals sedentary, and having no head, pro- 

 vided with eyes or antennae. 



Animals without eyes or antennae. Body ex- 

 ternally setigerous for locomotion. Articu- 

 lation distinct. 

 Animals aquatic, without eyes or antennas. 

 Body not externally setigerous. Articulation 

 indistinct. 



Animals provided generally with eyes but not 

 with antennae. Body not externally se- 

 tigerous. Articulation distinct. 



1 Milne Edwards is said in the public journals to have discovered that some Annelida are not provided with 

 red blood, but the distinguished Savigny stated the same fact so long ago as the year 1823, for in his Systhne 

 des Annelides he places Clepsine among his Hirudine'es. Nay, even Cuvier, who first distinctly pointed out the 

 group under the name of vers a sang rouge, has said that their blood is only generally red. Although herma- 

 phrodites, many of them require a reciprocal coitus. 



PoLYPODA. f NeREIDINA. 



Marine animals, having J 

 their body provided with di- i Serpulina. 

 stinct feet. L 



Aberrant Group. 



r LUMBRICINA. 



Apoda. 



Body without feet or a di-^ 

 stinct head. 



Nemertina. 



HlRUDINA. 



