PENNATULIDA. 



53 



Nr. i is entire and shows no terminal bulb; Nr. 5 and 6 are fragments of the rhachis; in the latter, 

 the upper end of the rhachis is undamaged; half of Nr. 4 is a naked calcareous axis, and only in the 

 lower part of the pen are some polyps preserved; Nr. 7 is rather damaged, broken, and the uppermost 

 32""" only a naked calcareous axis. By clearing of Nr. i and 6 in oil of cloves, quite whole, undigested 

 shells of Limacina are observed partly in the oesophagus, and partly in the gastric sac of several 

 polyps; at the locality in question, Limacina was especially numerous in the plankton. This fact, I 

 suppose, indicates that these sea-pens, although bottom animals, get part of their food from the 

 animal life of the surface, individuals from this part sinking to the bottom; in a similar way I have 

 seen larvae of lamellibranchs forming a prominent part of the food of Virgularia mirabilis from the 

 Sound. Sexual organs were not seen on clearing; nor did an examination by serial sections show 

 any such organs. Closer examination, on the other hand, has shown the following interesting 

 features with regard to the inner structure. From the dorsal longitudinal canal of the rhachis, trans- 

 verse canals issue at quite regular and somewhat short interspaces towards the periphery, where they 

 open partly directly into the gastric sac of the dorsal zooids, partly in the interspaces between the 

 zooids -- into a system of canals which is, otherwise, again connected with the zooids. These trans- 

 verse canals evidently correspond to the radiate canals* of the Virgularia (and also of other Penna- 

 tulids); here they are characterized by being in the form of a long funnel, narrow at the 

 dorsal main canal and widening at the peripherial end; their epithelium stains very intensely, so 

 that they are seen with unusually sharp outlines. In each transverse section only one or two such 

 dorsal radiate canals are generally seen. Into the ventral principal canal open radiate canals situated 

 in the middle of the rhachis; they are much larger and wider than the dorsal ones, but run also 

 towards the periphery; their epithelium also stains very intensely. These wide collecting canals 

 connect the polyps and the other (ventral) zooids with the ventral main canal of the stem either 

 directly, or indirectly through a network of canals with less intensely staining epithelium. The 

 collectiug canals are much less numerous, but much longer than the first-mentioned dorsal radiate 

 canals, and their course is a much less horizontal one; they go upwards or downwards, and only 

 rarely are more than two seen along-side each other. The small number of these collecting 

 canals, I suppose to be connected with the small number of the polyps; both features to which may 

 also be added that no sexual organs were observed - - might favour the belief that Prot. carpenteri 

 is only a young stage. 



The features given above of the Ingolf s specimens of this Protoptilum show the very greatest 

 correspondence with the Pr.aberrans of Kolliker; there is no doubt that these specimens might justly 

 be referred to this form (or the unnamed ones which Kolliker in the Chall. Report has added after- 

 wards as Nr. 2 and Nr. 3, which, however, no doubt belong to the same form). I have had the oppor- 

 tunity of seeing the originals in the British Museum, and I find no other differences between the specimens 

 of the Ingolf and the type-specimens of the Challenger than the fact that the enlargement of the 

 lower part of the rhachis in which the sexual organs were found, mentioned by Kolliker as character- 

 istic of Pr. aberrans, is wanting (as in the unnamed Nr. 2), and further that the colour of our speci- 

 mens is much more intensely red. The first feature: the presence or absence of an enlargement is certainly 

 quite a casual one, and the presence or absence of distinct sexual organs in this place is certainly 



