316 



It is known from P. varians by the much greater length of the 

 laminse, and, in its most developed part, by a stropg keel ou the 

 outer edge of each, not seen iu the portion sketched. 



5 (c). Petaloconchus? renisectus, var. Woodwardii. 



P. t. P. renisecto simili, sed muito miiiore, confertissima, am 

 compacta ; vertice nucieoso Bissoideo ; opercido parvo, dimidio 

 aperturcB cEquante, corneo, tenuissimo, extus parutn coticavo, 

 paucispirali, cicatrice centrali. 



Diam. spirse '15, aperturse "06. 



JJab. ? Sp. glom. m Mus. Cuming. 



This specimen has the habit of a distiuct species : nevertheless as 

 the inner structure appears exactly the šame, and as the shells are 

 most compactly crovvded, it appears probable that the sraall size is 

 due to the circumstances of habitat. It will be observed that the 

 cperculum presents a type of structure very distinct from that of 

 Bivonia glomerata aud its congeners, as well as from Vermetus, and 

 much more nearly related to Siphonium. As it agrees with that of 

 P. varians, it is fair to conclude that the other species are not 

 unHke. Theopercula were so very frail, thatafter digestionin weak 

 alkaU to remove the animal matter, it was not found practicable to 

 preserve them. This accounts for their absence from the other 

 species. 



6. Petaloconchus nerin^oides, n. s. (fig. 6.) 



P. t. P. renisecto simili ; sed rubro-fusca, rugulis spiralibus plu- 

 ribus ; intus solida ; laminis ut in P. renisecto sitis, sed 

 validis, labriim versus scepe biangulatis ; catnera eztema 

 minore. 

 Diam. spirse "3, aperturae '1 poli. 

 Hub. Australia. Mus. Cuming. 



Although the plan of structure is the šame as in P. reni/orinis, 

 yet the remarkable strength of the laminse, smallness of the outer 

 chamber, aud difl'erence of colour, appear to justify at least a tem- 

 porary separation. Iu Mr. Cuming' s group, the creatures have 

 stretched their tubes so long that even the straight part is often 

 found laminated ; and transverse septa are seen at the other end. 

 In some parts the body only occupies about a third of the section 

 of the shell. 



7. Petaloconchus cereus, n. s. (fig. 7 .) 



P. t. haud parva, irregulariter spirali, cerea, solida, albida, au- 

 rantio tincta ; anfractibus planatis, ad sedem angulatis, 

 nodosis ; laminis parietalibus tenuibus, curtis, in medio sitis, 

 subperpendicularibus, parum arcuatis, interstitio haud parvo ; 

 camera externa majore ; plica una parva columellari, in medio 

 šita. 



Diam. spirse '56, aperturae '18 poli. 



Hab. In Insulis Philipinarum ; legit H. Cuming. Sp. unic. in 

 Museo suo. 



