401 
of his description is taken from an Annelide, and the other part is 
founded on a fragment of a shell found on the deck after a storm in 
the Bornean sea—very likely the Ianthina exigua, which, like Sili- 
quarius, has a deep notch in the lip, and is of about the same dia- 
meter as the specimen figured: “II flotte et nage dans la mer et il 
enfle son manteau en forme de voile.” 
Dr. Gray has formed for the genus a section Siliquarina in the 
family Vermetide. It seems to me to have the same relation to 
Vermetus as Haliotis to Stomax and Delphinula. Tenagodus differs 
principally from Vermetus in the operculum, which is spiral like that 
of Torinia, composed of a spiral band ciliated at the margin, forming 
a cylinder or cone the axis of which is filled up by a series of spiral 
radiating cells, and which in the last whorl looks like a Robulina or 
Semen medicaginis (subgenus Siliquarius). In Siliquaria lactea, 
Lam., the axis is filled up with transverse parallel septa without 
radiating cells (subgenus Pywipoma, Mérch). The marginal spiral 
band appears composed of radiating bristles, united at their base by 
corneous matter, only leaving the points free. Dr. Chenu has figured 
(in his ‘Manual,’ p. 321, f. 2308*) an operculum quite different 
from those I have seen, and which, if correct, must belong to a distinct 
genus, perhaps to the typical Tenagodi. The foetal shell is wanting 
in all the specimens I have seen, except in Siliguaria lactea, where it 
has the form of Ampullaria, the under part of the outer lip being 
produced, and of a brown colour. Chemnitz has described the 
young shell as Helix incisa, and Brocchi as Serpula ammonoides. 
Sowerby, in his ‘Genera,’ first showed the real nature of the former, 
and Bronn of the latter. In the subgenus Siliquarius the surface 
of the shell is curiously fissured transversely in a manner I do not re- 
collect to have seen in any other shell. I am very much inclined to 
regard this outer layer as a calcareous epidermis, like that of Lucina 
pennsylvanica, L. tivela, and Margaritifera. In Siliquarius lacteus 
this layer is very little developed. The aperture is round and simple 
in all the specimens Ihave seen. Martini has figured (pl. 2. fig. 13 B) 
a species with the outer lip strongly dentated. Perhaps it is Sipho- 
nium nebulosum, Dillwyn, with rubbed spines, The slit is wanting in 
some species in the first whorls ; in all it becomes closed more or less 
with age. In the subgenus Pyzipoma it is closed by a lamella, but 
not filled up outside. 
In the fossil species Siliquaria dubia, Defr., and S. lima, Lam.., 
the slit is very short like that of Pleurotoma ; in the fossil genus 
Agathirses it appears to be different. 
The typical Tenagodi seem, according to Rumphius, to live on 
tocks and corals. The subgenus Siliquarius lives always in sponges 
like Vulsella. The only affixed species is the fossil S. forina, 
Defr., figured by Dr. Chenu on Cerithium giganteum ; perhaps it 
must form a new genus, if not the young of dgathirses, Montfort. 
Tenagodus is only found in tropical seas (East and West Indies) ; 
Siliquarius is subtropical. Pyzxipoma is found in Australia, the 
West Indies, and perhaps at the Cape of Good Hope. 
* Perhaps copied from Adams’s ‘ Genera.’ 
No, 442.—Proceepinés or tHE Zootocicat Soctety. 
