CLASS GASTROPODA 
323 
Amicula pallasii Middendorff, 1846 
Bulletin, Imperial Academy of Sciences, St. Petersburg, 6: 117. Sibirische Reise, 163; 
PI. 13, figs. 1-9. 
Testa subinterna, occulta, pallio obvoluta, mucronum fossula postica 
sola externe conspicua; elevata aut subelevata, 98 ad 110 in junioribus, 
120 in adultis maximis; ovalis, elongata. Lat., 1; long. 2^. Valvae albidae, 
leves, fragiles; tegmentum subnullum, cordiforme, posticum, in imo muc- 
rone; ratio long., 1 ad clivi lat., L}4-2; articulamentum suturis connatis 
evanidis; suturae laterales infra sulco obsoleto indicatae, supra sulco pro- 
fundiori, utroque limite carinuka concomitato; valvae intermediae, trans- 
versim si medio dissecares, antica et postico parte congruentes forma; 
valva ultima anormis, articuli superficie plicatula, apophyses margine 
tamen integro; apophyses terminal, %. 
Limbus luxrians in pallium extenditur, totum animalis dorsum rotun- 
datum obtegens, valvae obcolvens et occultans, solis octo aperturis minutis, 
rotundatis, in lines medians, quibus aditus ad umbonem valarum patet; 
color squalido lutescens; epidermis dorsalis undique versum fasciculis pilo- 
rum rubicundorum crinita; pili bini, terni xx cet., plerumque octoni et 
ultra; microscopio spectata epidermis dorsalis inter pilorum fasciculos 
pubes exhibet, stroma tamen spinulis latentibus nullis ornatum; epidermis 
ventralis spinulis erectis rarioribus munita, quarum singulae una ab altera 
spatio, spinulae fere longitudinem aequante, distant. Branchiarum seres 
postica branchiae parcae, circ. No. 29. Adulti maximi longitudo, 67 mm.; 
latit., 48; altit., 21. (Middendorff.) 
Shell nearly concealed by the girdle, a somewhat heart-shaped tegmen¬ 
tum only being visible at the apex of each valve; elevated at an angle of 
98°-110° in the young, 120° in the large adults; oval elongated. Valves 
white, smooth, fragile, the tegmentum cordiform, posterior. Slits in an¬ 
terior valve, 6-8; posterior valve, 2. Girdle roundly covering the entire 
back of the animal, except for 8 small rounded holes along the median line; 
color dingy buff; dorsal surface bearing all over unequal bunches of red¬ 
dish hairs, appearing to be sparser in the young. Branchiae extending for¬ 
ward two-thirds the length of the foot. Length, 67; breadth, 48; height, 
21 mm. (Tryon and Pilsbry, Manual of Conchology.) 
Type in Academy, St. Petersburg. Type locality, Okhotsk Sea. 
Range. Arctic Ocean, Bering and Okhotsk Seas, and eastward to the 
Shumagin Islands, Alaska. 
Described as Chiton pallasii. 
[925 ] 
