,1861.] M, O. A. L. MORCh's REVIEW OF THE VERMETID^. 149 



superne leviter injlexa, inferne obsoletissime effusa ; strict in- 

 crementi bis arcuatim retrojlexce. 

 Operculum aretispirale, inferne convexum, superne concavum, setis 

 longis multifidis munitum. 



A7iimal viviparu?n, descriptum sequente modo in opere dido 

 ' Voyage de I'Astrolabe,' " En avant du mufle est un appendice 

 raediau vertical, evase en entonnoir, susceptible de s'allonger ; un 

 pen plus en avant en est un autre qui se recourbe vers I'opercule, et 

 qui n'est peut-etre que le pied lui nierae renfle. Ce sont les ana- 

 logues de ceux que nous avons vus pairs dans les especes precedentes, 

 et dent nous ignorons I'usage. Le pied a de plus, sur le cote droit 

 seuleraent, un petit tubercule pointu, tel qu' Adanson* I'indique 

 dans son esp^ce. La cavite respiratrice est ample, et uue branchie, 

 a lamelles jaunes, cylindriques et rigides, se rebrousse par-dessus le 

 manteau et fait saillie a I'exterieur." 



Testa natalis nautiliformis sed asymmetrica, arcuatitn regulariter 

 granulosa ; operculum nudum membranaceum planum. 



Cuvier, in 1830f, was the first to mention Vermeti with a spiny 

 operculum, a fact probably communicated to him by the naturalists 

 of ' L' Astrolabe,' just returned the preceding year from their second 

 circumnavigation. 



The form of the aperture varies in the same species from being 

 exactly circular to ovate or reniform. A peculiar obliquity in the 

 aperture of some specimens in each group led me to recognize the 

 species of this genus before the lids were found ; this obliquity is 

 very likely occasioned by the long opercular bristles often forcing the 

 animal to withdraw the operculum obliquely, and, by their frequently 

 touching the border of the aperture, stopping the growth of the tube 

 at that side. The bristles, giving the lid quite the appearance of a 

 broom, are much worn, and have the interstices always filled up with 

 fine clay. The use of these bristles in the economy of the animal it 

 is difficult to guess, but it may very likely be the same as that of the 

 spiny homs on the lid of Cymospira gigantea, Pall., and the pallets 

 of Xylotrya (Leach), which in shape are not very unlike the bristles 

 of Stephopoma roseum, Quoy & Gaim. (see Plate XXV. fig. 11). 

 The bristles seem under the microscope longitudinally canaliculated 

 outside ; but I believe this canal in reality is the hollow interior, as I 

 have distinctly seen under the compressor the air-bubbles move in 

 the interior and even out into the lateral spines. The sculpture of 

 the unborn shells has a striking resemblance to that of Argonauta 

 oryzata, Meusch., and is continued in a part of the first whorl of the 

 affixed shell. In Stephopoma tricuspe, Morch, the granules look 

 under the microscope like holes with a dark border. The small 

 holes described by Quoy and Gaimard as covering the shell of Ste- 

 phopoma roseum, and supposed to be formed by some parasitical 

 animal, will perhaps prove to be an optical deception occasioned by 

 the sculpture. 



* Adanson has mentioned a little opening in the border of the mantle, but not 

 in the foot. 



t Cuvier, Reg. Animal. 1830, iii. p. 109. 



