A REVISION OF THE GENUS STKGANOPORELLA. 251 



much thickened at the cominencemeiit of its descending 

 portion, which is usually far from the condyles. Tube origi- 

 nating far below the angle of the cryptocyst, conspicuously 

 long, with a complete wall well raised above the basal wall; 

 its opening nearly vertical. Median process formed by 

 distal and lateral upgrowths from the roof of the tube, which 

 is largely exposed as the floor of the wide cavity of the 

 median process, b opercula rare, broad and short, with 

 strong ri-shaped main sclerite, the insertion of the occlusor 

 muscle being unusually elongated. Submargiual teeth ves- 

 tigial. A opercula relatively small, weak, and undifferen- 

 tiated. 



Curtis I., Bass Strait (Hincks Coll., B. M., 99.5.1, 29). 



The specimen to which this description refers is a large 

 Escharan or bilaminar plate, about 70 mm. long, probably 

 part of a larger colony. The surface is undulating, and 

 although no secondary plates are given off, one is apparently 

 developing as a ridge near the peripheral edge. Mr. Hincks 

 had merely labelled the specimen "Curtis,'^ but this, as I am 

 informed by Mr. Kirkpatrick, is Curtis Island in Bass Strait. 



The conspicuous features of this species are the extremely 

 long tube (fig. 3) and the great length of the post-opercular 

 (proximal) part of the zooecium, due in large measure to the 

 distance by which the condyles are separated from the base 

 of the median process. The Escharan habit should not be 

 left out of account. I am inclined to think that Smitt, 

 Hincks, and others have gone a little too far in denying the 

 value of the characters of the zoarium in distinguishing- 

 species. 



The edge is unusually high, and is the summit of a ridge, 

 triangular in transverse section, which is sharply separated 

 laternlly from the post-oral shelf. This is well developed, 

 tubercular, and rounded, and is well separated from the 

 cryptocyst. The oral shelf is smooth and narrow ; the con- 

 dyles are small, the oral arch well raised. The cryptocyst is 

 thick and tubercular, with small pores. It is sharply angu- 



