Remeio of Recent Geological Literature. 255 
to the pedicle opening, or delthyrium, as it has recently been termed by 
Prof. Hall, whether it is of one piece, the "deltidium," or composed of 
two pieces, the "deltidial plates." It is here shown "that the deltidium 
in all species possessing it (the Protremata) is an embryological, or ne- 
pionic feature, which may or may not continue to the ephebolic period; 
while the deltidial plates in other brachiopods (the Telotremata) appear 
later during the nealogic and ephebolic period, or may never be devel- 
oped." The deltidium "is a shell growth from the dorsal side of the 
body [in the typeembryo stage] which afterwards becomes attached to the 
ventral valve, and is then considered as belonging to it," while the delti- 
dial plates first commence to grow out from each side of the delthyrium 
during nealogic growth, and are secreted by the ventral mantel lobe; a 
fundamental difference. 
The presence of a dorsal anal opening in the Lyopomata and its absence 
in recent Arihropomata the author admits is difficult to explain, its so- 
lution depending "upon whether the class is to be considered as pro- 
gressive or degraded." In Silurian, Devonian and Carboniferous deposits 
forms occur belonging to the Protremata and Telotremata in which there 
has been observed a dorsal foramen, the "visceral foramen" of authors. 
"This character," he says, "is evidently in no way connected with the 
pedicle opening, but points to the existence, in the early articulate 
genera of an anal opening dorsal to the axial line, as in the recent Crania. 
* * * In reference to this character and the obsolescence of the eyes 
the class must be viewed as retrogressive since paleozoic time. * * * 
Progressive in concentration of posterior elements, expansion of anterior 
elements, and limitation of pedicle opening to one valve." 
The post-embryonic stages are then defined, also giving examples and 
figures of the "nepionic [young], nealogic [youthful], ephebolic [mature], 
and geratologic [old age] periods." 
"Another aspect of growth and decline is manifest when the size of 
individuals and the chronological history of the groups are taken into con- 
sideration. Each geaus and family began with small representatives, 
and rapidly developed the more radical varieties of structure. Then 
came the culmination and final reduction in size, with abundance of 
geratologous and pathologic forms. * * * The culmination of gera- 
tologous growth results in the reversion of the animal to its own nepionic 
period and is called the nostologic stage." Among clinologic and nosto- 
logic genera are mentioned Cistella, Ouoynin, Atrctia and PUitydia, which 
have lost many of their adult progressive ancestral features and, there- 
fore, represent early stages of growth in other modern species. 
Annual Report of the Department of Mines and Agriculture, New South 
Wales, for the year 1891. This report presents, in a very admirable way, 
the results of mining operations in New South Wales for the annual 
period it covers. In the case of some of the valuable minerals there 
are comparative tables giving the annual output year by year from 1865 
to 1891. The value of the yearly product of minerals by the colony is 
between six and seven millions sterling. The total value of minerals 
