454 Br. 0. Herrmann — Distribution of Graptolites. 



As regards the formei- position of the Graptolites in the living state, 

 two diiferent views are extant. Hopkinson, Lapworth, and Zittel 

 represent all Graptolites with the acute extremity of the sicula 

 always directed upwards, and state that in their opinion the Grapto- 

 lites formerly lived in this position. A Didyinograptus consequently 

 turned the point upwards, and the two branches grew downwards. 

 Other naturalists, as, for example, Hall, Nicholson, Tullberg, Linnars- 

 son, and Brogger, choose such a position that the sicula, regarded as 

 a point, is always placed below, while the branches stretch upwards. 



Direct evidence as to the correctness of one or the other view 

 cannot be obtained, seeing that from the position in which we now 

 find their remains in the rock, we cannot ascertain what position the 

 living animals took in the Silurian sea. After their death they fell 

 to the bottom, and then laid themselves upon one side. Even, in the 

 expanded much-branched Dichograptidse, the appearance of which, 

 especially when a central disc is present, may have had some re- 

 semblance to that of a Medusa, no conclusion as to their former 

 position can be drawn from their present position upon a rock- 

 surface. 



The zoologists, however, refer to the fossils of arborescent form 

 which are certainly very nearly allied to the Graptolites, and lived 

 at the same time with them. These, such as Dendrograptus serpens, 

 Hopk., possess a true stem from which branches and twigs issue 

 at one end, while the other end terminates in a radiciform nodule. 

 These forms may very probably have been attached, or have lived so 

 that the points of the twigs formed the superior extremities, but not 

 so that the branched part was turned towards the depths, and the 

 stem with its nodose termination directed upwards. Here, how- 

 ever, the nodose, and therefore probably the lower part, was un- 

 doubtedly the older, i.e. the starting-point. In Dictyograptus, Lapw,, 

 a genus which is also abundantly branched, there is no stem bare of 

 branches ; in it the whole hydrosoma runs out into a point (sicula). 

 This is also the starting-point ; the free extremities of the twigs are 

 the younger parts of the hydrosoma. If we place the starting-point 

 below in this case also, the whole hydrosoma represents a funnel 

 opening upwards, certainly the natural position. If we reason in 

 like manner in the case of Didymograptus, etc., there also the sicula 

 must be placed at the bottom, and the branches and hydrothecae 

 represented as stretching upwards. 



We have therefore regarded the sicula as an equivalent whole, 

 without taking into consideration whether the budding takes place 

 sometimes at its pointed, sometimes at its broader end. Prof. 

 Leuckart very kindly called my attention to the resemblance 

 between the Graptolites and existing animal forms, and upon the 

 last-mentioned point I have, after mature consideration, adopted, 

 with full conviction, the views of my honoured instructor. The 

 Graptolites have, therefore, always been figured by me with the 

 sicula below, and the branches directed upwards. 



Funiculus. — Hall has given the name of " funiculus " to the part 

 of the hydrosoma which, in the forms of Dichograptidee possessing 



