4 2 



PENNATUUDA. 



his supposition that Protocaulon belongs to Anthoptilum, and Protoptilum to Virgularia, is quite errone- 

 ous, he is assuredly right with regard to Microptilum. He has had young forms of Pavonaria 'fin- 

 marchica in which he finds the polyps isolated, thus forming two simple alternate rows, along the 

 rhachis as in Microptilum; and later (Bull. Mus. Comp. Zool., vol. XI, p. 4), he has described a young 

 specimen of Pavonaria finmarchica of a length of 7o mm , in the following manner: When most devel- 

 oped, there are two polyps in each oblique row, supported by two-lobed spiculose calicles; between 

 the wings there are four to six scattered zooids. Toward the upper part of the peduncle there is 

 but one well-developed polyp, with or without an additional young bud, in the oblique rows; and 

 here the calicles have the apex bilobed slightly, or not at all, and terminating in a single pointed 

 group of spicula. This part agrees essentially in structure with the genus Microptilum K611iker. 

 The somewhat imperfect figure that he gives (1. c. PI. I, fig. 3) of part of a young Pav. finmarchica 

 is presumably of this described specimen. By a comparison of this figure with those on PI. II of the 

 Ingolf's specimens, there will be scarcely any doubt left as to the identity of the form. That the 

 question is really of Pavonaria finmarchica - - this species being the only Pavonaria known from the 

 northern Atlantic --is made further certain for the American specimens, by the fact that Verrill has 

 evidently had sufficient material for comparison and sufficient intermediate stages. But without such 

 intermediate stages, I am equally certain with regard to the Ingolf specimens; a direct comparison 

 even with specimens of two feet or more will show the essential agreement in the features not 

 dependent on the growth. In the developed form of P. finmarchica the polyps are present in large 

 numbers, arranged in oblique rows and united in these by coalescing into wings; the single calyces 

 are completely coalesced almost to the very edge; the oblique transverse ridge thus formed shows, 

 however, in well-preserved specimens a series of long points supported by spicules on its abaxial sur- 

 face, apparently one such point for each polyp. A more thorough examination will show that to each 

 polyp-calyx belong really two long points, but the two adjoining each other in neighbouring calyces are 

 either coalesced, or one, the inner one, atrophied. Often, however, the oldest polyp of each wing, the 

 one at the dorsal edge of the wing, shows both its calyx-points; and when, as is frequently the case, 

 even in specimens of two feet or more, a solitary polyp is placed between the wings, the calyx of this 

 polyp has two ventral or ventro-lateral points. Here, as in the solitary young polyps at the lower border 

 of the rhachis towards the peduncle the edge of the calyx on the side turned towards the stem is 

 seen to be deeply hollowed; this may partly be seen also in the wings, when the attention is drawn 

 to it. The polyps have evidently some difficulty in retracting completely; at all events they are 

 generally somewhat expanded; their fore-part and tentacles (in spirit) are chocolate-coloured or deep 

 reddish brown. I have measured the largest of the spicules of the calyx to a length of 1.280""" and 

 a breadth of o.o8o mm ; on an average they are 1.024""" l n g an d 0.048""" broad, (Kolliker, however, 

 gives their length to 1.8 2.i mm , their breadth to 0.06 o.o8 mm ); these dimensions, as will be seen, agree 

 very well with those of the Ingolf specimens, and I may add that the form of the spicules is the 

 same. Both the form and especially the considerable size of the calyx-spiciiles exclude Halipteris 

 absolutely; this holds good also with regard to the long calyx-points; and the question could only 

 be of referring these young stages to the genera Halipteris and Pavonaria\ of northern Pennatulids 

 they are the only ones in which the calyx is provided with two points. 



