BRACHXOPQD A—THOMSON. 
13 
cademis (Jackson), L. antarchca (Bloclimami), L. fulva (Blochmann), L. blochmanni 
(Jackson), L. concentrica (Hutton), L. tateana (Tenison-Woods), and the new species 
described below have a southern distribution and include Oligocene-Miocene southern 
fossils. Whether the other known southern recent species, Terebratula moseleyi 
Davidson, Terebratula vitrea var minor Davidson (not of Philippi), Cape of Good Hope, 
Terebratula uva Davidson (? of Broderip), Heard Island, and Liothyrina winteri 
Blochmann, belong also to this genus or to Liothyrina must remain uncertain until the 
presence or absence of the median septum has been ascertained. 
From a study of the spicules occurring in the arms, Blochmann (1906 and 1908) 
divided the species then considered as Liothyrina into two groups, distinguished by 
the presence or absence of a row of spicules as the base of the cirri (Cirrensockel), which 
may conveniently be termed cirri socles. The group in which they are absent, which 
includes Liothyrina vitrea , occurs chiefly in the Atlantic Ocean and the Mediterranean 
sea, with the exception of one species in Japan and one of! Madagascar, to which must 
now be added a species in Australia. The group in which they are present, which 
includes Liothyrella uva, embraces the majority of southern forms, and also one species 
each in the Arctic, the Mediterranean and the Pan ami c regions, while L. uva itself ranges 
from southern American waters as far north on the west coast as the gulf of Tehuantepec 
in Mexico. Blochmann’s conception of the relationship of the various species with the 
latter group is of interest. From the fact that each of them has its peculiar district and 
does not transgress into the district of another, and from the further fact that these 
various districts hang together, he concludes that the smaller species, such as artica, 
' affinis, clarkeana, antardica, davidsoni, winteri , and perhaps moseleyi have arisen as 
t local forms' of a species which has gradually extended its distribution, each form 
corresponding to a new district which has been occupied. The occurrence of arctica 
between Iceland and Greenland and of affinis in the Mediterranean is difficult to 
account for on this theory, for the districts of these species do not join up to those of the 
southern forms. In any case such a theory of the relationship of the species of so old 
a genus seems much too simple to be credible, and takes no account of the extinct 
Terebratulids- of the Tertiary. 
From a study of the spicules in a series of Liothyrella antardica in different 
stages of growth Eichler suggests the possibility that cirri socles may be present in the 
young stages of Liothyrina vitrea and other forms, their absence in adolescence being due 
to a later resorption. 
Liothyrella fulva (Blochmann) furnishes a critical case for determining the value 
of BlochmamTs two divisions. The similarity in shape of this species to Liothyrella uva 
caused Davidson to unite it with the latter. If the specimen described below is correctly 
assigned to L. fulva , the latter species agrees further with L. uva in the presence of a 
fine radial ornament, and is without doubt a species of Liothyrella. Nevertheless in 
L: uva , which is a smaller species, cirri socles are present, while in L. fulva they are 
absent. Blochmann’s division, therefore, conflicts with a division of the species based 
