116 



A close examination of the recent species which he has observed 

 has convinced Mr. Broderip that although one valve of the sheU is 

 always fixed or imbedded in the chamber formed in the hard sur- 

 rounding substance, the tube is not necessarily continued into a com- 

 plete testaceous clavate shape, and that consequently the character 

 assigned by Lamarck to the genus requires emendation. The fixed 

 valve is in all these species continued on to the tube. In Mr. 

 Cuming's the perforated shelly plates are situated not far from 

 the throat of the tube, one on either side ; while in Mr. Gold- 

 smid's the perforated plate is single, and seated at the anterior or 

 greater end of the ovate chamber, being in the smaller individual 

 joined laterally to the anterior ventral edge of the fixed valve, and 

 in the larger one wholly isolated from it. In all the specimens the 

 anterior edge of the fixed valve is surrounded by the naked wall of 

 the chamber. 



After remarking on the difficulty of clearly defining species where 

 the roughness or smoothness of the surface of the shell and even its 

 shape may depend upon the greater or less degree of hardness of 

 the material of which the chamber is formed ; where colour also is 

 absent ; and from specimens of which the tubes are broken ; Mr. 

 Broderip proceeds to suggest the following distinguishing characters. 

 The first two may, he remarks, hereafter prove to be mere varieties, 

 although he is strongly disposed to regard them as constituting 

 distinct species : 



Clavagella elongata. Clav. camerd elongato-ovatd ; valvd liberd 

 elongatd, subtrigond, convexd, externe concentrice valde rugosd, 

 intus nitente ; umbone acuto. 

 Hab. in Oceano Pacifico } 

 Mus. Goldsmid. 



The wall of the coral chamber against which the free valve rested 

 gives as exact an impression of the external rugosities of that valve 

 as if the valve had been applied to a surface of wax. 



Clavagella lata. Clav. camera rotundato-ovatd ,• valvd liberd 

 latiuscukl, subtrigond, subconvexd, externe concentrice rugosd, 

 intus nitente ; umbone subrotundato. 



Hab. in Oceano Pacifico. 



Mus. Cuming. 



Both valves are nacreous internally ; and the muscular impres- 

 sions, especially in the fixed valve, are very strong. 



Clavagella Melitensis. Clav. testd subrotundatd, rugosd, intHs 

 subnitente ; tubo longitudinaliter corrugato. 



Hab. ad Melitam. 



Muss. Cuming, Miller. 



It is not impossible, from its locality, that this may turn out to 

 be M. Audouin's species, if that should prove to be a true Clavagella. 

 M. Sander Rang's remarks, however, go far to show that a Sicilian 

 Shell referred to this genus, has been incorrectly so referred, in as 

 much as it has no fixed valve. The one described above has the 

 fixed valve continued on to the shelly tube as in the other recent 

 species of the genus Clavagella. 



