14 G. LIXDSTROM, ON THE SILURIAN GASTROPODA AND PTEROPODA OF GOTLAND. 



Brought forward 1 40. 

 Jfollvsca 



Cephalopoda about 100 



Pteropoda -. — 5 



Gastropoda .- --- 17-1 



Lainellibranchiata about 80 g-g 



Molluscoida 



Bryozoa about 50 



Brachiopoda 150 g^,) 



Echinoderinata 



Asteroidea 2 



Echini. idea 1 



Criuoidea .-. -- 180 jg^j 



Anthosoa about — - — 100 



Graptolitce - - 5 



Spongiai — - 10 



Dubious organisms (Algpe probably) and others 5 



TentaculitcE about 5 



Total 1,007 species and varieties. 



It is to be observed that the iiuinber of si)ecies in some groups has been rated 

 somewhat low and that in all probability a detailed rt^search will considerably increase 

 it. As it now stands we see that the Gastropoda vie in numerical strength with such 

 large groups as the Crinoidea and surpass all the others. 



The minor details in the distribution, geographical and geological, of the Ptero- 

 poda and the Gastropoda may be learnt from the annexed lists ^), in which first the 

 chief localities or local regions are given in 27 columns, and then in the six last columns 

 a summing up of their stratigraphical distribution. Under the headings of the loca- 

 lities, a signifies the lowest stratum, shale or sandstone, b the intermediate limestone 

 or the oolite, c the uppermost limestone. When a species is recorded as found only in 

 a and c this has been considered equivalent to its having been found in h also or in 

 all strata. 



As to the names of the localities, it should be borne in mind, that some of 

 them are intended for a small district around a central point. Thus Hall chiefly 

 means the strata c in the canal near Westos, but also the strata near the shore and 

 at Halls huk. Wiiiiiiisudd includes the adjacent shores of FarSsund, as the strata of 

 Sandvik, Gothem and Jlara embrace chiefly the shore deposits at Gothemshammar and 

 a number of quarries opened westwards in the direction of Bara, where a little hill, 

 Bai^a bdcke, contains the saine fossils. Linde and Fardhcin comprises not only the lime- 

 stone hills there, but also the marly and gritty shales. 



The limestone beds of Samsugn in Othem, those of Wialrasudd and Wisby as 

 well as others are very rich in shells of Gastropoda intermingled with those of Cepha- 

 lopoda. But all these localities are by far surpassed by the limestone of Sandarfve 

 kulle. This is one of the small hills, which in the central part of Gotland, a little 



*) See page 16 and the following. 



