( 694 ) 
mentions three other species of this genus (16, p. 22). Among my 
material for comparison is a specimen from Klein-Ruhde, to the 
west of Kattentack in the H-zone in Esthonia. This roek is some- 
what darker, more grayish; but yet examples are to be found among 
our pieces which perfectly resemble it, so that the correspondence 
may really be called striking. The deseribed Cornulites do not occur 
in it which it is true cannot surprise us im a piece of so small 
dimensions (7 X 6 >< 2 c.M.). 
Finally I wish to state that in a boulder of stromatopora-limestone 
in Gothland, I found analogous Cornulites-cavities, which petrogra- 
pbically does not altogether agree with our pieces. The place where 
it is found is immediately to the north of Högklint, on the field 
(not in the beach). But this fossil is of little importance for the 
further determination of the age of the rock, as most likely various 
species will be implied in the name of Cornulites serpularius SCHLOTH. 
which is usually given. 
Taking everything into consideration, it seems possible (perhaps 
even probable) to me that this Clathrodictyon-limestone comes from 
the H-zone in Esthonia or from its western continuation. 
In connection with this must be said that among the very nume- 
rous stromatoporae of the Hondsrug (of which speeifie determinations 
are hardly ever possible) two occur which from their characteristic 
astrorhizae may be called : 
Stromatopora discoidea LonsD. sp... .. 25, Pl. XXIV, f. 2. 
Both pieces, found in the “Noorderbegraafplaats” and in the “Violen- 
straat’’ in Groningen, consist of fine-grained crystalline (stromatopora-) 
limestone ; the former is all over white and therefore closely resem- 
bles Clathrodictyon-limestone, the latter is rather grayish and also 
partially weathered, which fact decreases the correspondence. 
This species, very common in Wenlock limestone from England, 
also occurs in the neighbourhood of Wisby in Gothland. Nicnonson 
calls those Gothland specimens however usually highly mineralised 
(25, p. 191), which with my material from Gothland corresponds 
but to this extent that this fossil occurs only as a not always very 
thick crystalline crust in marl or marly limestone. LinpstR6M records 
it only from 4 (16, p. 22), his youngest zone of the Upper Silurian 
of Gothland (/, Dams). Contrary to this I allege to have found a 
specimen (it is true somewhat differing in a smaller number of 
astrorhizae) in the calcareous marl immediately to the north of 
Hogklint, occurring there as firm rock; this fossil comes from a 
