Observations on the genus Rastrites and some allied species of Monograptus. 



7 



ber being just that stated by Ferner himself as characteristic of the species. The 

 insignificant variation in this respect observed in specimens from Dalarne seems 

 to me to be of no specific value, though it is a fact tbat examples from this pro- 

 vince have more frequently 8 thecte than 10 in the space of 10 mm. As the 

 original of the figure in question has been partly obliterated, another specimen, in 

 all essentials agreeing with the same, is represented in fig. 14. 



In a subsequent memoir »Researches into the Monograptidœ of the Scanian 

 Rastrites Beds», I have again under the name af Rastrites peregrinus recorded a 

 graptolite found in the zone of Cephalograptus cometa at Tomarp (p. 25, Pl. IV, fig. 

 29). Although the fragment deliueated agrees fairly well with Perner's description 

 and figures, it is too imperfect for an exact identification, and, considering its geo- 

 logical horizon, I now regard my earlier determination as less probable. 



The specimens from Skellgill illustrated in figs. 19 and 20 are much deformed 

 by lateral pressure, but I believe, nevertheless, their determination to be reliable. 



Localities. The above description is based on specimens from the follow- 

 ing localities: Sweden: Kongslena (Västergötland), Råsnäset near Motala 

 (Östergötland), Kallhol n (Dalarne), Tomarp and Nyhamn (Skåne); Bohemia: 

 »Colonie Haidinger»; England: Skellgill (Westmoreland); Scotland: 

 Dobb's Linn and Garpel Glen (Moffat). I have not seen the typical form 

 from any Thuringian locality, though its existence in this region also is very probable. 



Horizon. In Sweden the species seems to be restricted to the zone of 

 Monograptus triangulatus ; in Scotland it occurs in the zone of Monograptus gre- 

 garius; at Skellgill it is associated with Monograptus argenteus &c. 



Note. The three forms next to be described may, for the present, be treated 

 as varieties or mutations of Rastrites peregrinus, though it is most probable that 

 some one or other of them, when better known, will prove to be separate species. 



Rastrites peregrinus Barrande var. hybridus Lapworth. 



Pl. I, figs. 23, 24. 



1876 Rastrites peregrinus Barrande, var. hybridus Lapworth, Ou Scottish Mono- 

 graptidœ; Gèol. Mag. Dec. II, Vol. III; p. 313, Pl. X, fig. 5. 



1876 » hybridus Lapworth, Catalogue of the Western Scottish Fossils, PI. 



F fig- 4. 



1877 » peregrinus Barrande, var. hybridus Lapworth, On the Graptolites 



of County Down; Proc. Belfast Natur. Field Club, Appen- 

 dix, 1876—77; p. 127, Pl. V, fig. 2. 



1892 » hybridus Törnquist, Undersökn. öfver Siljansomr. Graptol. II; K. 



Fysiogr. Sällsk. Handl. Bd. 3 (Acta Univ. Lundensis. Vol. 

 XXVIII); p 4, Tafl. 1, fig. 2. 



1897 » » Frech, Lethsea Geognostica, I, p. 666, fig. 219:4. 



1901 » » Holm, Kinnekulle, p. 61, tig. 55. 



