BIHANG TILL K. SV. VET.-AKAD. HANDL. BAND. 3. N:0 12. 23 



tudinal ridge an obloBg scar, wliicli might be prodiiced by ths 

 "anterior occlusors." Some specimeus measure: 

 Length 9 mm. Breadth 10 mm. 



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Acrothele coriacea is the most widely spread species in tlie 

 strata with Paradoxides Forchhammeri. In the north I have 

 found it in loose stones at Lillviken in Jemtland, in the south 

 at Andrarum in Scania. It is also commou in the interjacent 

 provinces. In Westrogothia it oceurs at Kinnekulle and Lo- 

 vened; in Xerike at Sanna, Hjulsta, Vinala, and Vrana; in Oland 

 at Södra Möckleby. That it also oceurs in Bornholm is shown 

 by specimens sent by Professor Johnstrup; these are, however, 

 few in number, and it seems therefore to be rather scarce in 

 that island. 



At Andrarum a similar form oceurs in the limestone band, 

 above referred to, lying between the strata with Paradoxides 

 Kjerulfi and those with Parad oxides Tessini. I have only 

 examined some very few specimens, communicated from the 

 museum of Lund by Dr. Lundgren. They are not in such a 

 State that I will venture to express a decided opinion of their 

 relation to the preceding species, but, if not identical, they 

 are certainly nearly allied to it. I have prepared figures of 

 two specimens, the only ones tolerably perfect. The one (fig. 

 50) is an internal cast of the ventral valve. It is nearly cir- 

 cular, the length being 5,.'j mm., the breadth 6 mm. The um- 

 bone is perforated by a round foramen; it is not very excen- 

 tric, the distance from the anterior margin being hardly twice 

 that from the posterior. The other speciraen (fig. 49) is an 

 interiör of the same valve, in which the inner shell layers are 

 in part exfoliated. It seems more transverse, but the margins 

 are not quite perfect, and the real shape cannot, therefore, be 

 €xactly ascertained. The umbone is more eccentric ; it is per- 

 forated by a round foramen, and before that two minute pits 

 are seen, indicating that also in this there are on the exteriör 

 two wart-like protuberances. The shell surface is not visible 

 in any specimen; nor have I seen any dorsal valve. 



