SOME RARE AND INTERESTING SEA ANEMONES FROM PLYMOUTH. 67 



capitulum less. Body- wall thick, tough and opaque ; physa damaged, 

 but appears to be much smaller than in H. chrysanthellum, no sand 

 grains were attached, and no suckers were observable with a lens ; the 

 small size is well shown in Mr. Orton's sketches, as is also the fact that 

 the physa is letractible in this species, and thus agrees with the plate 

 and description of Haddon (Proc. Koy. Dublin See, 1889). The scapus 

 tapers at either extremity, and for a length of 20 mm. is coated with sand 

 grains attached to suckers, and within this portion the physa and 

 capitulum can be withdrawn. The capitulum is smooth, more delicate, 

 and somewhat constricted near the summit. 



Colour, pale yellowish buff, the mesenteries showing indistinctly as 

 paler lines. Tentacles and disk much as in H. chrysanthellum ; one of Mr. 

 Orton's sketches, comprising a tentacle and portion of disk and mouth, 

 shows the transverse bars, M-mark and the triangular brown patches 

 figured by Haddon ; but the form of these brown marks on the disk is 

 different. Instead of being " lenticular " the marks are triangular, with 

 the apex directed toward the tentacle. 



Haddon gave a comparison of the anatomical characters of the two 

 species of Halcanvpa, but a re-statement of the points of difference seems 

 advisable ; and ignoring for the present the colouration of the disk and 

 tentacles, the details are here given : — 



H. chrysanthellum. H. arenaria. 



(1) Physa large, globular, trans- (1) Physa smaller, probably 

 lucent, provided with small white without suckers, and retractible 

 suckers, and not capable of being within the scapus. 

 withdrawn within the scapus. 



(2) Scapus smooth. (2) Scapus with suckers to 



which adhere sand fragments 

 forming a more or less dense 

 covering. 



(3) Number of folds of the (3) Number of folds of longi- 

 muscular epithelium of the longi- tudinal muscle about 15. 

 tudinal muscle of the mesenteries, 



as seen in transverse section, 10 

 to 12. 



In addition to the above Haddon states that :■ — 



(4) " The oesophagus in section 

 is, relatively to the diameter of 

 the body, much larger in H. chry- 



