Some Recent GraptoUtic Literature. — Gurley. 41 
The Rastrltes slate is undoubtedly capable of subdivisions but the data 
are defective. A provisional arrangement of zones is proposed. 
The author is disposed to question the received opinion that the 
graptolites are closely related to the Hydrozoa as difficult to reconcile 
with the structure of Retiolites as set forth by himself and Tull- 
berg. Relative to the structure of that genus ( R. fjeinUzianus ) the 
views of the author are in complete accord with those of Mr. Holm 
given above. The relation of the last named species to Stomatograptus 
tornquisti, Tullberg is shown and the identity of Tullberg's species with 
Retiolites grandis Siiss, is established by comparison with specimens 
from Sixss's type locality. Retiolites obesus Lapworth he thinks should 
probably form the type of a new genus when better material is obtained. 
Passing rapidly over descriptions of species which possess little inter- 
est except for specialists we note the suggestion of Herr Tornquist that 
the genus DidyTnograptus be made the type of a new family, the Didy- 
mograptidge. It differs from the compound dichograptlds in having the 
sicula divided by a distinct wall from the two branches while in the 
dichograptlds the sicula merges without distinct boundary into the 
thecaphorous hydrosoma. In Dldymograqjtns moreover the branches 
are given off at different levels reminding one of the alternation of 
theca-formation in the diprionidian graptolites. Further on ( under 
Phyllograptus densus, Tornq.) we find that the theca in Phyllagraptus 
are inserted at the same level in whorls of fours. The structure in this 
genus is thai of four monoprionidion polyparies soldered back to back. 
No distinct virgulge were observed. The author thinks some specimens 
show a sicula with the point thrust up into the proximal thecal cycle, 
but adds that this requires confirmation. 
Besides the above outline which contains the gist of such parts of 
Herr Tonquist's paper as are calculated to interest the general reader, 
this excellent essay abounds in descriptions which well sustain the 
character of the Swedish graptolites writings for accuracy of specific 
definition and painstaking morphological study. 
The new species are : Clonograptus rohustus, Tetragraptus curvatiis, 
Didyraograptus gracilis, D. deeens, Climacograptus intenexus, Diplo- 
graptus hellulus. In addition to these many previously described forms 
are figured and their synonymy considered. 
Ootlands Oraptoliter, by Gerhard Holm; Bihang till K. Sv. Vet. AK. 
Handl., 1890, XVI, Afd. IV, No. 7, , 2 pis. Also Reprint, Stockholm, 
1890. 
This excellent paper contains the results of the author's studies of the 
graptolitic material from Gotland added to the State Museum, since the 
publication of Linnarsson's paper of the same name eleven years ago. ^ 
Linnarsson knew of but three species of Graptolites occurring in Got- 
land. Tullberg and Lindstrom subsequently increased the number to 
five. Mr. Holm has added three more so that the list now stands as 
follows: 
'Linnarsson G. Ofv. K. Vet. AK. Forli.. 1879, No. 5, pp. 3-12. 
