C L A V A G E L L A. 



Plate I. 



Genus CLAVAGELLA, Lamank. 



I'eKta bivalvis, sa^ros madreponisque perforaiis, ontice 

 bulbcBJurinis, postice in tubinn attenuata. Ttibus 

 ante valvas in spinis tubuliformibus terminoTis. 

 Valvce edentulee, intus margaritacece, ad marginem 

 ventralem Mantes; sinislra libera, dexlra in tubum 

 affixa. 



Shell bivalve, perforating rocks and matlrepores, an- 

 teriorly bulb-shaped, posteriorly attenuated into a 

 tiibe. Tube terminating in front of the valves in 

 tube-formed spines. Valves edentulous, pearly 

 within, gaping at the ventral margin ; left free ; 

 right fixed in the tube. 



In tlie fossil form, when the tube and valves are de- 

 tached from the stone in which the mollusk burrowed 

 when living, the Clavagella appears not unlike a rather 

 bulb-shaped aspergillmn ; the small spinous tubes with 

 which the large tube terminates, not, however, forming 

 as in that genus the margin of a perforated disk. But 

 when the shell is seen in situ, in a recent state, it is ob- 

 served that the valves are not rudimentary points forming 

 part of the tube, as in aspergillum, but are much more 

 advanced and expanded, one only being fixed to the 

 tube and forming part of it, while the other is free and 

 moves on its hinge. Thus our present genus is exactly 

 intermediate between Fistula, having both valves quite 

 free within the tube, and Aspergillum, having both 

 valves soldered into the tube. 



Mr. G. B. Sowerby appears to have been the first 

 to discover the existence of the genus in a recent state. 

 Having obtained permission to scrape away the matrix 

 from what was supposed to be a burrowing Aspergillum, 

 in the British Museum, he ascertained its true nature, 

 and pviblished a figure and description of the first 

 kno-svn recent species under the name of Clavagella 



APERTA. 



The eight or nine species now known are found in 

 the Mediterr.auean, Australia, and the Pacific. 



Species 1. (Fig. a, b, c, Mus. Brit.). 

 Clavagella balanorum. Cla. testa paivd, camera uvata, 



valv'i sinistra inrgulanter rugata, subtrigona, apice 



unguiculato, acuniinato ; tubn brcriusculu, com- 



presso, Icevi. 

 The balanus Clavagella. Shell small, chamber 



ovate, left valve rather trigonal, irregularly 



wrinkled, with ungmculated acuminated apex ; 



tube rather short, compressed, smooth. 

 ScACCHi. Philippi Enum. Moll. Sic, torn. ii. p. 1, tab. 



xiii. p. 2, a, b, c. 

 Hab. Jlount Pausilypus. Mediterranean. In groups 



of Bal.ani. 



The specimen in the British Museum which we have 

 figured, has been named as above by the authority of 

 Bisliaijes. 



Species 2. (Fig. «, b, r, Mus. Brit.). 



Clavagella aperta. Cla. tei^td in camera lata decum- ' 

 benti ; valva sinistra trigona, irregidariler nigatd, 

 apice fix acuminato ; tubo lato, maryine late rcjlexo 

 ei expanso, irregulariter late laqneato, interdmn 

 duplieato. 



TiiE OPEN Clavagella. Shell lying in a broad 

 chamber ; left valve trigonal, irregularly wrinkled, 

 apex scarcely acuminated ; tube broad, margin 

 widely reflected and expanded ; irregularly broadly 

 fluted ; sometimes double. 



SoWEi;iiv, G. B., Genera of Pecent and Fossil Shells, 

 No. i:i. 



Ilab. Mediterranean. 



The margin of the tube is broadly expanded and 



rather trumpet-sliaped. 



es3. 



(Mus. Brit.) 



Clavagella Philippiana. Cla. testa elongatd ; valva 

 sinistrd trigona, arcuatd, extiis nigatd ; tubo elon- 

 gate, ad latera subconstnicto, ad terminum vix 



December, 1872. 



