270 SYNOPTIC COLLECTION. 



not by the way of the Neotremata or Protremata, he places 

 the Telotremata next the Atremata. 



The Neotremata and Protremata branch off from the 

 Atremata at a much lower geological horizon than the 

 Telotremata. According to Beecher the Neotremata have 

 a protegulum like that of the Atremata and a Paterina 

 stage when the pedicle passes out freely between the 

 valves. According to Schuchert the pedicle opening in 

 this order is restricted throughout life to the pedicle valve. 

 Even if this be true with the forms so far described, we 

 predict that other forms will be discovered which have 

 the pedicle opening common to both valves in the nepi- 

 onic stage. 



For this reason we shall take up the Neotremata next, 

 bearing in mind that more investigations are needed on 

 the fossil forms belonging to this order, as well as on the 

 early stages of development of existing species. 



BRACHIOPODA. NEOTREMATA. 



One of the more primitive members of the Neotremata 

 is Paterula (PI. 656, figs, i, 2. P. bohemica Barr.). It has 

 a horny shell and when young is similar to Paterina, but 

 later, layers are put on the brachial valve (fig. i) posteriorly 

 to the beak which cause the beak to become internal and 

 the shell circular in outline. The pedicle valve (fig. 2) is 

 differentiated from the brachial by having a notch in the 

 margin which remains open in the adult (fig. 2). The 

 arms or brachia in Paterula are two single spirals without 

 limy supports. 



Another genus, Discinisca (No. 657, D. laevis Sow.), has 

 the protegulum of the brachial valve at the margin in the 

 youngest stage and later near the margin, but with growth 

 the protegulum becomes surrounded by more layers, as 

 seen in No. 657. The edge of the pedicle valve (No. 

 657) is notched on the margin for the passage of the 



