Development and Mode of Growth of Diplograptus. 247 



by branching. If the siculae, remaining in connection with the 

 parent colony, had developed their own^ central discs, the 

 latter must appear, by analogy with the primary rhabdosome, at 

 the first central disc, where, however, no indications of such 

 secondary central discs have been observed. The antisicular 

 ends of the secondary stipes connect directly with the antisicular 

 end of the primary stipe, thus forming that connecting stem for 

 which I adduced Hall's term " funicle." While the central disc 

 of Diplograptus^ though not in secondary position, but in origin, 

 is identical with Hall's central disc, Wiman is certainly right in 

 disapproving the application of the term "funicle" for the con- 

 necting stem of Diplograptus; for, while the latter, in JDiplo- 

 graptusjis apparently formed by the. connection of the antisicular 

 ends of the secondary stipes, that of the Dichograptidce is the 

 product of branching. 



Wiman objects to the comparison of the siculae-bearing capsules 

 with gonangia, and sees in them gemmating individuals, evidently 

 referring to his interesting observation of gemmation within 

 individuals among the Dendroidea. In the apparently complete 

 series of growth stages of Diplograptus pristis described in this 

 report, under the assumption that the "gonangia" were only 

 organs of asexual propagation, and the siculge consequently only 

 buds; sexual generation would on this supposition be entirely 

 eliminated, and this is most improbable. If it be supposed now 

 that gonangia, which are not preserved, existed somewhere on 

 the hydrothecse (the appendages observed by Hall might be ad- 

 duced here), and that these sexually produced larvae, then it is 

 inconceivable that these could have developed anythmg but 

 siculae ; for the growth of the whole colony, as well as that of 

 the stipes, starts clearly from siculas. Hence we would have 

 the same product, siculae, by sexual generation and a sexual 

 gemmation, which is improbable again. The capsules agree, as 

 their description shows, wholly with the gonangia of the Ser- 

 tularians in their general features. The fact, also, that the 

 larvae reached such a high stage of development within the 

 capsules is not without analogy among the Hydrozoans, e. g., 

 Sertularia cupressina discharges larvge already ciliated ; Tubularia 

 aoronata even "actinulae" with tentacles. Retaining the com- 

 parison of the Graptolites with the SertularianSy the budding of 



