208 SIDNEY F. HABMER. 



species agree in their lialnt, in tlieir diuiorpliic opei'cnla 

 (probably associated with the absence of ovicells), and in the 

 highly developed chitinous epitheca which overspreads the 

 entire zoariuni. E. clathrata differs from E. obtecta in 

 having its frontal calcareous wall composed of irregular bars, 

 iustead of a simple, perforated, calcareous lilm, and in the 

 fact that there is no large space between the frontal epitheca 

 and the calcareous walls. 



I feel doubtful whether Euthyris woosterijMacGillivra}',^ 

 is rightly referred to this genus ; but, on the other baud, 

 Carbasea moseleyi, Busk (1884. p. 5C), perhaps belongs 

 to it. 



The largest colony of E. clathrata measures about 18'5 

 cm. or 7 J inches in length. The branches are 2 to 4 mm. 

 wide, averaging about o mm. near their free ends, but lessen- 

 ing towards the base of the colony, which appears to have 

 been attached by a narrow base Avithout rootlets. A branch 

 4 mm. wide has about thirteen orifices in each oblique row. 

 The colour is brown in the older parts, yellowish near the 

 ends of the branches. The zoarium frequently bifurcates, 

 showing some tendency to form a unilateral cyme. The 

 terminal divisions (PI. 16, tig. 18) may reach a length of 3"5 

 cm. without bifurcating, but the ordinary length of the 

 divisions is not more than 1*5 cm. The frontal surface is 

 somewhat convex, the opposite surface flatter. The calca- 

 reous walls of the zocecia are arranged as follows : — The 

 lateral and terminal walls are everywhere complete, and are 

 perforated by numerous pores. At the proximal end (fig. 22) 

 the two lateral walls pass continuously into one another in a 

 regular curve, which forms the base of the zooicium, and is 

 placed some distance within the basal epitheca (fig. 26, h. ep.). 

 At the distal end the lateral walls appi'oach one another 

 basally, and are separately inserted into the basal epitheca, 

 forming a linear mark (figs. 22, 27) constantly shorter than 

 the zo(ecium, but varying in length ; this is connected with 

 the similar part of the next zoa3cium by a chitinous " meseu- 

 ' ' Pioc. R. iSoc. Vict..' (N. S.), ill, 1891, p. 71. 



