ANNULATA 39 



Phyllopods, Copepods, and utlier existing orders of Entomos- 

 traca. Only a few obscure forms, doubtfully referred to the 

 higher division, Malacostraca, have been found in the carboni- 

 ferous and Permian systems. The secondary strata contain 

 abundant remains of Isopods, and of lobsters and hermit-crabs. 

 True crabs (Brachyura) abound in the oldest tertiaries. Air- 

 breathing insects and Arachnida existed even in the palseozoic 

 age ; the " sombre shades" of the carboniferous forests were 

 not " uncheered by the hum of insects ;" nor were the insects 

 blind, like those which now inhabit the vast caverns of Ken- 

 tucky and Carniola. The Articulata which come latest are the 

 Cirripedes, whose lowest family appears in the lias ; while the 

 Balanidm are only found in the tertiaries. 



The number of fossil Articulata catalogued and described 

 forms but a very small proportion of those which have pro- 

 bably existed. Bronn enumerates 1551 fossil insects, 181 

 arachnids, 89i crustaceans, and 292 anellides. Darwin de- 

 scribes 69 fossil cirripedes, 12 of which are living species. 



Class I.— ANNULATA. 



(Worms, Tube- Worms, Nereids.) 



Char. — Body soft, symmetrical, vermiform, annulated, with 

 suckers, or setae, or setigerous tube-feet ; blood of a red 

 colour in most. 



The peculiar markings on the surface of the old Cambrian 

 slate rocks, conjectured to afford the earliest indications of the 

 existence of marine worms, are not without suspicion as to 

 their origin. The so-called " Nereites " bear considerable 

 resemblance to other equally ancient impressions which have 

 been described as Zoophytes, under the name of Protovirgu- 

 laria (fig. 3, i). No such doubt attaches to the worm-tracks 

 which abound in the thin-bedded sandy strata of the forest- 

 marble ; and the " Cololites" of the lithographic limestone are 



