240 



Type C. altum Sowb. and with it C. seotilabrum Gould, C. pauper- 

 culum Sowb., and C. funiculatum Bens. 



These species, which have been included in the genus Mcgalomas- 

 toma, are essentially different from the remarkable shells of the Wt si 

 Indies coming under that genus, although the single species M. Antil- 

 lanun has much the same character. Their habitat, general aspect, 

 and especially the double peristome, which is quite obvious posteriorly, 

 where the inner plate has a nick on one side or the other, give them a 

 marked affinity. They group with Tortulosa, Pupina, Registoma, and 

 similar eastern genera. 



Genus Ostodks. T. parva, turbinata, solida, ossea, albida, spira- 

 liter sulcata interdum undulata, profunde umbilicata : apertura fere 

 circularis ; peristomate simplici, fere continuo ; fauce porccllanfi. 

 Operculum corneum, multispirale, sutura modica. Iucolsc vibraculis 

 subulatis, tenuibus ; oculis haud pedicellatis. 



Type Cyclostoma strigatum Gould, including also Cycl. plicatum 

 Gd. (C. apiae Reel.), C. obligatum Gd., C. tiara Gd., C. flavum Brod., 

 and probably C. margarita Pfr. and C. euomphalus Phil. 



This small group of shells, which has been included in the genus 

 Cyclophorus, § 3, PIr., comes nearer to Omphalotropis in the family 

 Pupinse. They are known by their bony structure, dingy white, un- 

 polished, striated, waved or indented surface, simple aperture, and 

 deep, spiral umbilicus, almost like Torinia. They are all from the 

 Pacific Islands, mostly from the Samoa group. 



Lucia. Ligamentum nudum (?) latum : valvis carinatis, apiculatis 

 delicate pictis, pallidis, angulato-punctatis, ultimo gibboso, umbone 

 centrali valde elevato; marginibus insertionis dentibus pectinatis nume- 

 rosis instructis. 



L. confoxsa Gould, on which this genus is founded, has nine promi- 

 nent pectinated teeth of insertion on the anterior valve, about twenty- 

 five on the posterior, and five or six on each side of the central valves. 

 The ligament, most likely, was finely imbricate. The posterior valve 

 is very remarkable, the hinder portion rising vertically so as to form a 

 right angle on the umbo. The pale lemon or cream color, delicately 

 variegated with shades of red, and the sort of triangular or squamose 

 puncturation, are quite characteristic. Ch. pelaloides G. doubtless 

 belongs to this genus ; though the details of the plates of insertion 

 were not examined. 



Both these shells are from the Pacific Islands, — the one from the 

 Feejees, and the other from the Sandwich Islands; and, so far as I 

 know, they are the only Chitons yet found at the Polynesian Islands. 



It is allied to Callochiton by its plates of insertion and central poste- 

 rior umbo, but differs in its marginal ligament, and general aspect and 

 ornamentation. 



