ZOOLOGY AND BOTANY, MICROSCOPY. ETC. 229 



made for Crotalocrinus and its ally Enallocrinus, and suitable diagnoses 

 are given ; this family is allied to the other Oamarata through Marsu- 

 piociHnus. 



Ccelenterata. 



Structure and Development of Colony of Pennatula phosphorea.* — 

 Herr H. F. E. Jungersen has had the opportunity of examining a series 

 of young stages of Pennatula pJiosphorea, of which he gives an account.. 

 To this he prefixes some notes on the anatomy of the adult form, dealing 

 with neglected or unobserved points in its structure. Attention is drawn 

 to the fact that a transverse section through one of the leaves shows that 

 all the polyps of one leaf are arranged in the same direction. Below the 

 pharynx the eight septa are continued into the axis through the gastric 

 cavity ; the two dorsal septa are lower than the rest and are of ecto- 

 dermal origin, while the other six, which are much thicker, more coiled 

 and shorter, are of endodermal origin. Gonads are never developed on 

 the two dorsal septa ; their filaments take no part in the work of digestion, 

 but are of use, thanks to their rich supply of cilia, in the circulation of 

 water. In the opinion of the author the dorsal and ventral primary 

 canals of the axis have a different morphological value to the two lateral ; 

 the latter do not appear to be in direct connection with the animals, but 

 communicate by small orifices with the median can -i Is. So little is 

 known regarding the developmental history of the Pennatulidse that 

 Herr Jungersen's observations, though incomplete, are of considerable 

 interest. The youngest specimen, which was 7 mm. long, consisted of a 

 single well-developed individual, the stem-polyp or the first individual 

 formed from the larva ; it may be called the axial individual or terminal 

 polyp. Above, it forms an open cup, at the edge of which are eight 

 processes formed by long calcareous needles ; this cup contains a re- 

 tracted animal with seizing arms. Below the cup the body is j)rolonged 

 in the form of a stalk, and below the lowest bud passes into a somewhat 

 enlarged peduncle, which appears to be colourless and was clearly fixed 

 in the bottom of the sea ; an internal calcareous axis is already developed. 

 There are five buds, four of which are lateral, while one lies in the 

 median plane of the axial individual ; the last has no tentacles, under- 

 goes no further development, and may be called the axial or terminal 

 zooid. It can be easily traced in later stages, and it was found that the 

 surface of the axis on wh^ch it is placed is that which is generally known 

 as the ventral surface. What has been called the ventral surface of the 

 whole colony must be called the dorsal, and the dorsal the ventral. The 

 uppermost leaf is always found on the right side of the terminal polyps. 

 "When four or five well-developed leaves have been developed on either 

 side of the axis the first lateral zooids begin to be formed ; these increase 

 in number as development goes on, but no regular arrangement could be 

 detected in them. In all cases it happens that there is no terminal 

 polyp in the adult colonies of Pennahda phosjjJiorea, though the young 

 stages always have one. This terminal polyp remains a purely vegetative 

 individual, the individualized part of which either disappears or becomes 

 converted into a zooid, while the rest of its body persists as the axis of 

 the colony. 



A comparison of the young stages of Benilla and Pennatula points 



* Vi<lenskab. Meddelelser, Copenhagen, 1888, p. 154: translated in Zeitschr. f. 

 Wisd. Zool., xlvii. (1S8S) pp. G20-49 (1 pi.). 



