BRYOZOA 87 



We may say with certainty that there are at least i5 species of Cyclostomata, in the 

 Antarctic collection, nearly ail of which are indentical with, or closely allied to, widely 

 distributed species, but as few hâve ovicells, and many are in an unsatisfactory state of préser- 

 vation, we cannot généralise on the Cyclostomata, and to attempt to give them names, for 

 future comparison is a most unsatisfactory task. 



STOMATOPORA 



The genus has been abundant and also widely distributed frorn Jurassic times to the 

 présent, and is represented in Arctic and Antarctic seas as well as in intervening régions. 



According to Ulrich Stomatopora dichotoma « Lamx. » occurs from the Trenton beds 

 to the présent time, and S. inflata Hall occurs in the Cincinnati group of beds ; also other 

 monoserial and some multiserial forms occur in the Paleozoic formations. 



Gregory and Urlich would separate the monoserial species as Stomatopora from the 

 multiserial forms, which they consider to be Proboscina, but this is a rétrograde step, which 

 cannot be accepted by those who are aiming towards a natural classification, unless some fresh 

 characters supporting the change should be discovered. In this genus we see uniserial forms 

 become bi-triserial, and further in a large number of gênera both uniserial and multiserial 

 growth occurs, as for example we may mention Membranipora, with M. pilosa, and M. monostachys 

 both sometimes uniserial; then M. catenidaria may occur in both conditions; in Smittia there 

 is in this collection S. reptans nov., in Hippothoa and Beania there are both growths, again in 

 Alcyonidium there is A. disjunctum Hincks, a uniserial form. 



Paleontology is not advanced by classification, in which convenience is the first consi- 

 dération, for though divisions are sometimes necessary, for arrangement of material, before 

 satisfactory characters are known, yet we must endeavour to find fresh characters to reveal the 

 classification nature has made for us. 



Stomatopora dichotoma (d'Orb.) 



Criserpia dichotoma d'Orbigny, Voyage dans l'Amérique méridionale, p 19, pi. IX. figs. 7-13. 

 Proboscina dichotoma d'Orbigny, Paléontologie française, p. S47. 



This is well figurée! by d'Orbigny and would seem to be the species subsequently 

 described as S. (A/ccto) dilatons Johnst., and has been thus mentioned by Btjsk, Aluer, Norman, 

 Lorenz, Sequenza, Waters, but I now consider the name dilatans, should be dropped for 

 dichotoma, though the ovicell not having yet been described, there will be some uncertainty, 

 until further spécimens enable us to learn more about the range of variation in the species. 

 S. repens S. Wood is closely allied, and it may well be that thèse two will hâve to be united. 



The zoœcial tubes are about o.i4 mm wide, whereas in S. divergens they are about o.og mm 

 internai measurement. A spécimen from Cape Horn, which Julliex had labelled T. pedata 

 Jull. is probably S. dichotoma. The ends of the zoœcia are round, measuring internally o.i4 mm . 



Habitat. — Exp. Antarct. Belge. 



N os 5;o, 5gi, Tangles VII. Lat. 70° 23' S.- Long. 82 47' W.; 480 met.; +0.8 C. 



