THE GRAPTOLITES. 365 



not all, of the specimens of Monograptus may have been 

 fixed to the sea-bottom, or to objects lying or growing on 

 it, and not have been free-floating organisms, as has hither- 

 to been supposed, until at last they were separated from 

 their points of attachment by breakage or some other 

 natural cause ". Recently a remarkable description has 

 appeared (14) giving an account of specimens of Dipto- 

 graptus pristis Hall and D. pristiniformis Hall from 

 the Utica Slates. In these specimens the stipes occur in 

 "compound colonial stocks which appear in the fossil state 

 in stellate groups ". From observations on the specimens, 

 the author infers "that the colonial stock was carried by a 

 large air-bladder, to the underside of which was attached 

 the funicle. The latter was enclosed in the central disc, 

 and this was surrounded by a verticil of vesicles, the 

 gonangia, which produced the siculae. Below the verticil 

 of gonangia and suspended from the funicle was the tuft 

 of stipes," the latter being so arranged that the " sicula- 

 bearing end of the single stipes appears in the compound 

 colonial stock as the distal one ". The paper is only an 

 abstract of one which is promised shortly, and geologists 

 will await with interest a full account of these remarkable 

 specimens. The structure described as a funicle can hardly 

 be looked upon as the analogue of the " organ" described 

 by Hall under that name (which by the way has been 

 proved by Brogger and Holm to be celluliferous in many 

 species, so that Holm is doubtless correct when he says 

 that a funicle has not been found in any graptolite). It 

 is remarkable that the author should explain what he 

 means by the assertion that the chitinous capsule which 

 encloses the " funicle ' : on the specimens described is 

 identical with the "central disc ' : of the compound 

 fronds of numerous Monogr apt idee, for no geologist, as 

 far as I am aware, has described Monograptidcc with com- 

 pound fronds, unless Dairon's specimens be taken as such. 

 The early writers on graptolites looked upon the num- 

 ber of stipes possessed by graptolites as a character of 

 prime importance in defining genera, such forms as Dicho- 

 graptus, Tetr agraphia, Didymograptus and Monograptus 



