344 BULLETIN OF THE 



Family ADDISONIID^. 

 Genus ADDISONIA Dall. 



Addisonia Dall, Proc. U. S. Nat. Mus., 1881, p. 405, April, 1882. Jeffreys, P. Z. S. 

 1882, p. 673 ; lb., 1884, p. 148. Fischer, Man. de Conchy 1., p. 757, 1885. 



Addisonia lateralis Reqdien var. paradoxa Dall. 



Plate XXV. FiKS. 1 a-e. 



Addisonia paradoxa Dall, Proc. U. S. Nat. Mus., 1881, p. 405, April, 1882. 



Gadinia lateralis Requien, Coq. de Corse, p. 39, 1848. Petit, Cat. Moll., pp. 92, 264, 



1869. 

 Gadinia excentrica Tiberi, J. de Conchyl., VI. p. 37, pi. ii. fig. 6, 1857. Weinkauff, 



Conch. Mittelm., IL p. 177, 1868. Dall, Am. Naturalist, p. 787, 1882. 

 Tylodina excentrica Monterosato, Not. intorn. Conch. Medit., p. 57, 1872. Locard, 



Cat. Moll. Mar. de France, p. 67, 1886. 

 Addisonia eccentros Jeffreys, P. Z. S. 1882, p. 673; P. Z. S. 1884, p. 148. 

 Addisonia lateralis Dautzenberg, J. de Conchyl., 1886, p. 205. 



Habitat. Mediterranean. North Atlantic, both European and American 

 shores, living in 50 to 640 fms., dead in a wider range of depth. 



This curious form was not collected by the Blake. I find that most Euro- 

 pean malacologists have agreed * that Requien's very poorly described and un- 

 figured shell is identical with Tiberi 's Gadinia excentrica. I am in doubt as 

 to the identity of the American and European forms. They belong without 

 question to the same genus to whose conchological peculiarities I called atten- 

 tion seventeen years ago (Am. Journ. Conch., VI. p. 19, 1870). The figures, 

 descriptions, and specimens I have seen of European origin all indicate the 

 shell as very much smaller than our American specimens; these, when adult, 

 average 12.0 mm. in length, which is frequently much exceeded. I do not 

 feel justified in keeping them separated on the mere ground of size, but would 

 suggest the question to be determined by some European naturalist who may 

 be able to examine the dentition and soft parts. Like Neritina^ Cocculina, and 

 Cranopsis asturiana, this creature retains the intromittent organ which seems 

 to have become obsolete in the majority of shallow- water Rhiphidoglossa (see 

 Verrill, Trans. Conn. Acad., VI. p. 256, 1884). 



This mollusk is well entitled to family rank, for reasons set forth in my 

 paper above mentioned. The absence of the brush-like uncini is a remarkable 

 character, while the remaining teeth are unmistakably Rhiphidoglossate. The 

 presence of the verge which led my friend Dr. Paul Fischer to refer this genus 

 to the Tsenioglossa (Man., p. 757) can hardly serve that purpose now that his 

 own Cranopsis asturiana is shown to possess it. 



* See Mr. Dautzenberg's excellent article above cited. 



