222 REPORT ON THE STATE CABINET. 



feature is shown under the illustrations of the structure of these bodies 

 on Plate ii. 



In R.ETI0L1TES, the common bodj occupies the central portion of the 

 stipe, giving origin to a series of buds or polypites on each side, while 

 the central axis is filiform and does not divide the interior canal. 



In some species, the comanon body seems also to have more extensive 

 functions ; for in such forms as G. diver gens and G. gracilis^ there is a 

 long slender rachis, or tubular body, destitute of cellules except at its 

 two extremities, and apparently consisting of a solid axis and a common 

 body, from which originate, at regular intervals, simple small stipes with 

 solid axis, common canal, and cellules. 



This appears to be one step farther in our knowledge of the origin or 

 mode of development ; but it shows that a common body or main axis 

 may produce in one part celluliferous stipes, and its extremities develope 

 only cellules, as we see in the continuation of the main axis of G. gracilis, 

 and G. divergens, where the continuation of this common rachis is marked 

 by marginal cellules of the same character as those of the lateral stipes. 



The common body (Ccenosarc) appears to perform in this case the 

 double fiuiction of developing the buds — polypites, which elongate into 

 stipes with cellules, and also of simple cellules at its two extremities; or 

 we may consider the celluliferous extremities of the rachis, or main axis, 

 as analogous to one of the lateral celluliferous stipes. These individual 

 stipes, if separated from the main axis, would have the appearance of 

 entire graptolites with the attenuate lower extremities ; and it seems to 

 me not improbable that some of the simple monoprionidian species, which 

 have been regarded as entire bodies, may in fact be only the separated 

 portions of fronds like that of Q. gracilis and similar forms.* In the Ser- 

 tularians we have something analogous to this mode of development. 

 Some of the species have cellules along the common or main trunk, and 

 produce at intervals branches or branchlets in place of cellules ; others 

 have a common body, or main stem, entirely destitute of cellules, but 

 producing branches on each side (opposite or alternate, as the case may 

 be), which branches bear cellules only. 



So long as this rachis gives off only celluliferous stipes, it is analogous 

 to those parts of the simple Graptolites which I have termed the funicle, 

 having within itself the sources of this development of the several parts. 

 The mode of development differs from that of the branching forms, 

 inasmuch as the branches proper arise from a division of a cell-bearing 



*■ [See also Ctriocjeaptus ; Carruthers, Geological Magazine, 1868.] 



