206 



The Philippine Journal of Science 



1915 



Because of its interesting systematic position Cornularia mi- 

 nuta is worthy of careful anatomical study. However, my 

 material is so limited in amount and so poorly preserved that I 

 have found it impossible to make a thorough or detailed investiga- 

 tion of the anatomy. The few observations recorded here were 

 made on specimens preserved in formalin. 



The extremely thin, horny envelope contrasts strongly with 

 that figured and described by von Koch (1890) and Cavolini 

 (1785) for C. cornucopias; it averages 0.0008 millimeter in thick- 

 ness on the stolons and 0.001 millimeter in thickness on the base 

 of the polyps. It is wrinkled throughout, and although closely 

 applied to the ectoderm in some regions, it is as a rule separated 



from it by a considerable space 

 (fig. 3 a). On the stolons the 

 envelope appears smooth and 

 transparent in surface view, but 

 sections show that it is wrinkled. 

 On the basal portion of the 

 polyp the envelope is rather 

 opaque and in surface view has 

 a rough, corrugated appearance 

 (fig. 2), which sections show to 

 be due to wrinkling and to the 

 presence of foreign particles 

 rather than to inequalities in 

 thickness. 



As von Koch says (1890), in 

 speaking of C. cornucopise, this 

 skeleton is a product of the 

 ectoderm, similar in origin, ap- 

 pearance, and function to the perisarc of hydroids and of 

 Scjjphistoma. In C. minuta it has a remarkable resemblance, 

 particularly in sections, to the perisarc of certain hydroids; 

 indeed there seems to be no valid objection to the application 

 of the term perisarc to the horny outer covering of the species 

 of Cornularia, and I have so used the term in this article. 



The thin cup of perisarc within which the polyp retracts is 

 very flexible, as may be seen by a comparison of its shape in 

 the expanded polyp, where its distal and proximal widths are 

 approximately equal (fig. 4), and in contracted polyps where 

 it is nearly closed distally and considerably broadened basally 

 (fig. 2). This is in striking contrast to the condition in C. 

 cornucopik, where it is thick and stift", especially at the distal 

 edge of the cup. 



Fig. 3. A cross section of one of the stolons 

 of Cornularia minuta, showing the peri- 

 sarc (a), the endodermal canals (6), and 

 the thick mesogloea. From camera lucida 

 outlines. X202.5. 



