594 Canon A. M. Norman — Notes on the 



rounded corners there grow out nodulous processes, some- 

 times of very considerable size, and the slight central hollow 

 is filled up ; the structure now assumes the form of fig. 2 c. 

 When this nodulous growth is fully developed the zoarium 

 has a very peculiar appearance, and reminds us somewhat of 

 C. aurita, for the lateral avicularia of the two alternating 

 zocecia above nearly meet, and rarely actually coalesce with 

 the nodulous interzooecial growth which has been described. 

 The foregoing would appear to be a peculiar form of ooecium 

 and it is that which is the common one found in the species. 

 Very rarely, so far as my observations go, the form of a 

 shallow cap is taken on (fig. 2a), and this is the ooecium, which 

 Hincks figured from the Charlotte Isles. On one portion 

 of my specimen from the ' Vega ' Expedition a very different 

 form of ooecium is found (fig. 1 c) : I have seen it only on 

 zooecia in which the usual lateral avicularia are absent. The 

 form taken reminds one of a *' fool's cap,'' the front rim of 

 which is well rounded ; from this the ooecium narrows 

 gradually, and at the same time is also more depressed, 

 imtil it ends in a nodulous process. There are perhaps 

 twenty such ooecia together, though there is considerable 

 variation in their exact length ; close to them are, on other 

 zooecia, ooecia of the ordinary form (fig. 2 b). 



This is a very large species, which grows most luxuriantly 

 and is generally only loosely attached to the object on which 

 it is developed. It is of a rich deep brown colour, Hincks 

 says '' deep black," but, notwithstanding that statement, he 

 has given it a very expressive specific name in " nigrans." I 

 have compared my specimens with the type of Hincks, from 

 the Charlotte Islands, which is now in the British Museum ; 

 and the ' Vega ' locality, which I shall presently give, 

 aftbrds additional evidence that it is a circumpolar form. 



It may be the Rejjtoflustr'ma americana of d'Orbigny. 

 Smitt refers to that species, which was found at Newfound- 

 land, and he also states that the species from Labrador 

 which Packard recorded under the name " ? Lacroixii,^^ but 

 without any description, was, from specimens sent to him by 

 that writer, identical with what he calls "forma americana." 

 It must remain in some doubt to which of two forms Smitt 

 in that statement refers, for while his fig. 31 with its large 

 avicularia on the ovicells undoubtedly represents what I have 

 here described as C. unicornis, var. armifera, specimens 

 which he kindly sent to me named "forma americana " are 

 as undoubtedly that which I here refer to C. nigrans, Hincks, 

 which, among other marked characters, never has large 

 avicularia on the ooecia. 



