THE ANNALS 



AND 



MAGAZINE OF NATURAL HISTORY. 



[FOURTH SERIES.] 

 No. 83. NOVEMBER 1874. 



XXXVIII. — Notes on the Structure and Development of 

 Myriothela phrygia. By Professor Allman, M.D., LL.Dl, 

 F.R.S., Pres. Linn. Soc. 



In the structure and development of Myriothela phrygia are 

 many hitherto unrecorded points of high morphological and 

 physiological interest. The following notes contain some of 

 the more important results to which I have been led by a 

 recent study of this remarkable and little-known hydroid. 



1. The tentacles when extended are by no means the short 

 papilliform organs which we usually meet with in specimens 

 confined in our aquaria. They present, on the contrary, 

 when in complete extension a thin, cylindrical, and very 

 motile stem nearly a line in length, and a large terminal 

 capitulum very well defined and distinct from the stem. 



2. The animal is attached to fixed objects, not by the general 

 surface of hydrorhizal offsets (as is usual among the Hydroida), 

 but by the sucker-like truncated ends of short fleshy processes 

 which are given off from the basal extremity and, clothing 

 themselves with chitine, become permanently adherent to the 

 object which gives it support. 



3. The endoderm of the body is composed of numerous 

 layers of large spheroidal cells composed of clear protoplasm, 

 enclosing a nucleus with some brown granules and refringent 

 corpuscles. Externally it is continued in an altered form into 

 the tentacles, while internally it forms long villus-like processes 

 which project into the cavity of the body. Towards the free 

 ends of these processes there are abundantly developed, among 

 the large clearer cells, smaller easily isolated spherical cells 



Ann. & Mag. N. Hist. Her. 4. Vol xiv. 23 



