34 G. F. MATTUEW ON THE 



Tullberg- says Didyomma jlabeUiforme is very common in the youngest alumeuaceous 

 shales of Ostrogothia, and in other provinces also balls of authraconite^ are frequently 

 found in similar strata, which contain the same fossils, as shown when they are split open. 



Heisinger describes and delineates in his " Lethfea Suecica, supplementum secundum " 

 (1840) three species of graptolites, of which Dictyonema is regarded as a monocotyledonous 

 plant. 



Dictyonema flabelliforme. Eichw. (PI. XII, figs. 1, 2 and 3 a and b.) 



1727 — Mmci ramosi cupillamenta nigra, Bromell. 

 1840 — Gortjonia flahelliforme, Eichwald. Schichten syst. Eusslands. 

 1854:— Phijllograpta, Angelin. " Palœont. Scand.," I, p. iv. 

 Prior to 1857 — Fenestella socialis, Salter. ' Mem, Geol. Surv. G. B. Ill,' p. 536. 

 1857 — Graptopora sociali?, Salter. ' Proc. Am. Ass. Sei.' 

 1862 — Babdinopora flahelliforme, Eichwald. " Letliîea rossica." 

 1862 — Dicïi/OJîfma flimîijfm, Goeppert. " Uber die fossil flora, etc.," I, i, p. SC9. 



The following description of this species is given by Tullberg : 



" The hydrosoma forms by its brandies a flat extended disc,' growing out from a long narrow 

 sicula, which in its distal pait divides into two branches, which immediately again give ofT new 

 branches; by reiterated dichotomy a multitude of sub-parallel branches appear, connected by tine 

 chitenous iilaments, which in short, almost regular distances are stretched out nearl}' horizontally 

 from one branch to another. Every branch bears, as it appears, two series of hydrothecse, alternating 

 with each other. The horizontal chitenous threads seem always to arise from the apertural edge of a 

 hydrotheca ; in certain foims there is seen one thread extending from every hydi-otheca — this is not 

 the case in Hisinger's specimens; on others, on only one of two thecse, which seems to be most com- 

 mon for examples from Fagelsang and for that fromPiperviken, in Norway ; on other specimens again, 

 only every third or fourth theca bears one chitenous thread extending to the nearest branch ; this has 

 been observed on several specimens from Abj", in Ostrogothia, which are presei'ved in the State 

 Museum at Stockholm. The hydrothecœ are to be observed only on well-preserved specimens, and 

 on these with difficulty ; they seem to form elongated tubes, with the apertural edge scarcely i^roject- 

 ing forward ; sometimes there aie to be seen long impressed lines indicating interior septa. On a 

 length of 10 mm. there are 10 to 15 hydrothccaî. There arc no traces, of a vergula. 



"To separate from each olhei', as ditierent species or even as varieties, those forms which have a 

 different number of horizontal filaments, seems to be erroneous, their number even in the same 

 specimen being variable. 



" This species attained a considerable size, individuals of 15 to 20 ctm. in length having often been 

 found. Yet at some horizons the specimens are commonly small. The individuals have lived sociablj' 

 together, of which the shales of the youngest Scandinavian Cambrian rocks, covered with their polj'- 

 paries, afford evident proof 



" This species occurs always at a fixed horizon, namely, in one of the youngest beds ^ of the Camb- 

 rian system, which is called the Dictyonema shale." 



Herr Tullberg adds the following note : 



' " Anthraconite or swine^tone is crushed and powdered bj' the peasantry of Sweden as a medicine for sickly 

 domestic animals. Doses of this powder are given especially to sw^ine, from w'hich circumstance also its name is 

 derived. Solutions of swinestone are in some parts of Scania in great demand as articles of trade." 



- See TuUberg's note further on in regard to the form. 



^ This is the view of the Scandinavian palœontologists, who exclude the Tremadoc group=Ceratopyge beds, 

 from the Cambrian system. 



