192 G. LINDSTROM, ON THE SILURIAN GASTROPODA AND PTEROPODA OF GOTLAND. 



Several specimens have been found in the limestone of the hills of Sandarfve 

 and Linde. 



This species comes very near to the Lower Silurian Holopea exserta Forbes, 

 Mem. Geol. Survey vol. Ill, p. 347, but is rather not so much ventricose. 



3. Macrocliilina fenestrata n. 



PI. XV tig. 17—18. 



Shell elongate, slender, conical, with five Avhorls in the only, fragmentary spe- 

 cimen. These whorls have a nearly conical outline and are very little convex, the suture 

 is shallow. The surface is almost smooth, reticulated by transverse and longitudinal, 

 impressed lines of extreme minuteness, forming regular, fenestrate quadrangles, relati- 

 vely more quadrate and larger than in M, cancellata. The aperture is elongate, acu- 

 minate and narrow below, widened and rounded above. The outer lip is thin, the 

 inner one is thick and somewhat tortuous. H. 12 millim., br. 5 millim. 



A single specimen has been found in the limestone of Samsugn in Othem. 



Fam. XIV. SUBULITIDiE n. 



Shell elongate^ fusiform, aperture ohlong, narrow, slightly, hut most distinctly canali- 

 culated in the superior corner near the columella and thus a short siphon is formed. Whorls 

 generally straight, conical, smooth and unadorned and the suture very shallow. 



In this family I enclose such palaeozoic shells as Subulites and Euchrysalis. Bu- 

 limorpha Whitfield and Fusispira Hall probably also belong here. What characteri- 

 zes them all, besides the elongate and smooth shells and the narrow aperture with in- 

 complete peristome, is the important feature of a distinct apertural canal, situated ex- 

 actly as in all Siphonostomata and quite as much developed as in several of them, 

 where it has attained its smallest dimensions. This will be found on comparing such 

 genera as Pisania, Metula, Mangelia and especially Daphnella with Subulites, as will 

 be done more in full further on. 



We see, consequently, in this family the most ancient representatives of the great 

 section of the Siphonostomous shells. Hitherto the oldest known species of that 

 group have been found in the Triassic strata of St. Cassian in Austria. Shells bearing 

 affinity to Fusus and Fasciolaria, if not strictly belonging to these genera, but at all 

 events to the section of the Siphonostomata, have been described by Laube ^). The 

 limits of the range of the Siphonostomata in time must then be removed as far back as 

 to the youngest beds of the Lower Silurian, where there are species of Subulites found 

 in the LeptaBua limestone of Sweden. In Esthonia species of Subulites have also been 

 discovered in the contemporaneous strata. 



') Fauna der Sohichten von St. Cassian, III Gastrop. Denkschriften der Akad. der Wissensch. zu AVien, 

 Bd 28, 2e Abtheil., 31. 



