Reviews — Dr. G. Linddroni's Silurian Oasteropoda, etc. 39 



described, four of which are new forms. The author discusses the 

 question of the affinities of this genus to recent Pteropods, which 

 have been disputed by Haeckel and Neuniayr, and points out tlae 

 significant fact that, with other resemblances, there are, in some 

 fossil species, two peculiar longitudinal septa on the inner surface of 

 the shell, similar to those present in several of the Cleodorte and 

 Styliol^. 



Some small detached shelly plates, with conical or cordate out- 

 lines, are regarded by the author as belonging to the Chitonidse. 

 They were named Chelocles by Davidson and King, who thought 

 that they might have .formed part of an operculated coral. Their 

 affinities to Chiton are not altogether free from doubt, since the two 

 apophyses on the anterior margins of the plates or valves of recent 

 Chitons, are wanting in these fossil forms. They are, however, 

 similar to the forms placed by Barrande under Chiton, and the 

 author has discovered that their surface ornamentation entirely 

 agrees with that of the Cliitonidse. Their symmetrical form indicates 

 that they do not belong to the pedunculate cirripedes. 



To the family of the Patellidaa belong two species of Tryhlidium, 

 Linds. In this genus the muscular scars occur as six disconnected 

 paii's, arranged in a somewhat elliptical form, and the apex of the 

 shell is anterior. It approaches vei'y closely to Metoptoma, Phill., 

 but this form has a truncated area below the apex, which is directed 

 backwards, and the muscular impression is said by De Koninck to be 

 continuous. 



For the conical shells usually known in this country under the 

 names of Capulus or Acroculia, Lindstrom adopts Conrad's name of 

 Flatyceras, and he includes also in this genus Platystoma, Gonr., 

 Orthonychia, Igoceras and Strophostylus, Hall, and Naticopsis, M'Coy. 

 The examples of this genus exhibit great variations in form ; to this 

 may be owing the long list of synonyms of P. cornutum, the 

 commonest of all the Gasteropoda of Gotland. 



The family Bellerophontidae, represented by the genera Bellerophon, 

 Mont., Cyrtolites, Conr., and Tremanotus, Hall, is regarded as belong- 

 ing to the Gasteropoda and nearly allied to Halioiis. As synonyms 

 of the typical genus are included Bticania, Carinaropsis, and Phrag- 

 mostoma, Hall, and also JFaagenia and Waagenella, de Koninck. No 

 fewer than 13 species of Bellerophon are recorded from Gotland, all 

 of which are new, with the exception of the widely-distributed B. 

 trilobatus. Sow. There are also seven new species of Gyrtoliies and 

 two of Tremanotus. One of these latter, T. longitiidinaJis, is, however, 

 identical with Bellerophon dilatatus, Sow. ; as the type specimen of 

 this form shows distinct traces of the characteristic apertures on the 

 dorsal keel, though they are not mentioned either by Sowerby or by 

 M'Coy, who more fully described the species. 



The family Pleurotomarida3, including Pleurotomaria and Miirchi- 

 sonia, is represented in Gotland by 39 species of the former and 15 

 of the latter genus, the large majority of which are new forms. 



The following genera are included by the author in Pleurotomaria ; 

 Iiiachus, His., Scalites, Conr., Baphistoma, Hall, Ilelicotoma, Salt., 



