BRACHIOPODA—THOMSON. 19 
the sides into stellate plates with spiny rays and large central discs presenting many 
“windows,” and finally into more slender, much branched, irregularly shaped, plates 
resembling the latter, but with the “ windows” so developed as to destroy the appear- 
ance of the central disc. The plates of the ventral body wall agree with the second and 
third types above described for the dorsal body wall. 
The spicules of the arms and cirri, on the other hand, are relatively very slender. 
The row of main plates is stoutest on the dorsal side at the proximal end, and these 
consist of irregularly stellate plates of three or four primary rays, which quickly branch 
and bear spines, the branches having a tendency to curve to assume a dorso-ventral 
direction. These main plates have at first a small central disc with occasional small 
“windows,” and when followed distally are seen to become more and more slender, 
common forms near the end of the arm being four-rayed stars like a Southern Cross 
or three-pronged spines of swastika shape. Similar forms but of decreasing size persist 
on the ventral sides of the arm and in the spizal arm, where still simpler forms with 
assegal or boomerang shapes occur. 
The cirri of the inner row bear no spicules, while those of the outer row possess 
small, distantly-spaced, spindle-shaped rods. Into the base of the latter row of cirri 
there project small irregularly pointed but frequently pyramidal plates in a fairly 
definite row, which fails on the ventral side, except quite sporadically. It is separated 
from the row of main plates by an intermediate series of larger, similarly shaped plates, 
often resembling a twicée-barbed arrow head with the points directed towards the cirri. 
This intermediate series, which is almost but not quite referable to a single row, 
persists on the ventral side almost to the proximal end. 
The row of plates at the base of the cirri appears to be homologous with the more 
massive cirri socles of smaller shells. In the presence of the intermediate row, however, 
the arrangement of the spicules presents more resemblance to that shown by Liothyrina 
vitrea than by Lnothyrella uva. The shell characters, however, and particularly the 
presence of the dorsal median septum and of the fine radial ornament prove the closer 
relationship of the species with the latter. The slender development of the spicules 
of the arms seems in this species and Lothyrella fulva to be a function of size. 
The species is distinguished from other recent Liothyrell@ by its great size, and 
is to be compared with fossil forms in the Oamaruian of New Zealand, such as L. gravida 
(Suess) and ZL. oamarutica (Boehm). With the former it agrees in length, but is not. 
quite so broad and not so angled at the sides. It agrees more nearly in shape with the 
latter, but is slightly broader, with broader youthful growth lines, and has a labiate 
instead of a marginate foramen. L. oamarutica in addition is frequently more strongly 
folded than any examples of the present species. 
The young shell from Foveaux Strait, described by me in 1915 as Liothyrina sp., 
possesses stout cirri socles, and much more massive spicules in the cirri, and is quite 
probably not the young of the present species, 
