130 MAZATLAN BITALTES 



tremely rare, burrowing in Cliama ; Lpool Col. — Fossil, 



near Eomc, Lamarck. 



Tablet 604 contains tbe remains of tlie valve. 



StTB-GENrs LEIOSOLE]NTS. 



Animal profunde in matricem penetrans, earner am capacem, 

 politam excavans, partem derelictdm explens prater tnhum 

 lav em partim bilobatum, ? siphones longos tenentem. Testa 

 Lithophago similis. 



If the animal, wben examined, proves to bave long, excur- 

 rent siphons, it must take generic rank perhaps in the neigh- 

 bourhood of MytUimeria, Co7ir. 



178. Leiosolenus spatioslts, n. s. 



S. t. dactyliformi, tenuissimd, eurtiori ; postice concentrice 

 undulatd ; umhonihus celatis ; incru^tatione calcarid, tenui, 

 cequaliter totam superficiem tegente, 'pleriimqiie pustidis trans- 

 verse conjlncnfihus munita ; marginibus antice et postice rotun- 

 datis, ventraliter subexcurvatis ; lined cardinali prcelongd, 

 margine dorsali curvato, subangulato, curtissimo. Camerd 

 obovali, spatiosd, nitidissimd : tubo nitidojjlus minusve elongato, 

 juxta cameram contracto, postice hilobato. 



Several chambers of this remarkable shell were found by 

 Mr. Darbishire ; always in the lower valves of Spondylus, and 

 generally open as if part of the burrow were excavated in the 

 rock. This may account for the loss of the shells excei)t in a 

 single instance. In the largest specimen, presented by him to 

 the Br. Mus., are seen two chambers, which, from the long 

 bUobed pipe of one of them, might be taken for the work of 

 an enormous Gastrochfcna. The pipes are however perfectly 

 smooth.within, while in G-astrochama they are comigated. The 

 bilobation is only at the extremities, the rest of the pipe being 

 irregularly circular, and much contracted at its junction with 

 the cell. As there is no evidenceof paUial sinus in the shell 

 (though it ma,y possibly exist,) it is probable that the con- 

 traction of the siphons takes place outside the body of the 

 animal. From an examination of a specimen bl-oken in the 

 line of axis of the cell and pipe, it appears that the creature 

 begins life Avith the shortest possible tube and a somewhat 

 conical cell : as it burrows deeper, it not only fills up the cor- 

 responding posterior space with concentric layers of shelly 

 deposit, pierced by the pipe ; but also proportionally shortens 



