T 



hrough the kindness of Professor L. Agassiz, I have been enabled to examine and 

 describe the Floridan bryozoa, collected by Count L. F. de Pourtales, during the ex- 

 peditions of the United States Coast Survey, in 1867 — 1869. In doing this, I have felt 

 the o-reatest interest in findino- well-known Scandinavian forms living there amon<>- 

 tropical and antarctical ones. This collection gives, consequently, a new confirmation 

 to the geographieal theory, first and clearest enonnced by Professor S. Lovéx, that the 

 deep-sea-fauna is a uniform one, connecting the north pole with the south through spe- 

 cies of animals, distinguished by their strong vital force and, therefore, also by their 

 great geologieal age. For the northern part of the Atlantic, this theory was already 

 demonstrated by showino- the aretic forms o-oino- lower and lower down to greater 

 depths, as they extended in a south direction. For completing the demonstration, how- 

 ever, it was necessary to stretch the investigations out över the southern areas. This 

 the Swedish government did by the expedition of the frigate Josephine 1869; and the 

 indefatigable and distinguished zoologist Dr. A. v. GoÉs sent home from S:t Bar- 

 tholomew one of the greatest collections from the West-Indian fauna. Among these 

 collections, belonging to the Stockholm-museum, much will, without doubt, be neces- 

 sary for completing the list of West-Indian bryozoa, here to be given. But other occu- 

 pations now take up my tirae, and I have been obliged to limit my task to the Pour- 

 tales collection. I have thus often had only a few specimens or incomplete ones 

 for examination, and from them it was very difticult to draw any conclusions with 

 certainty. And nowhere can a richness of specimens be more necessary than in the 

 study of the bryozoa, because the developmental differences, interesting as they are by 

 showing the evolution from the lower to the highest types, make it a matter of great 

 difticulty to characterize the species. 



In other animals wc are accustomed to look at these differences only as transi- 

 tory, and we define the species after their fullgrown stage; but here, in the bryozoa, 

 the differences are persistent in the single individuals of the colony, and the faculty 

 of propagation belongs to very different stages of the colonial development. Yet more, 

 can the colonial development begin from different stages in the series of differences, and it 

 can stop in different degrees of individual evolution and perfection. Hence it will often be 

 difficult, if not impossible, without a full knowledge of the entire development, to give 

 the characteristics for a species or to range it in its true genus or fainily. In a series 

 of papers on the Scandinavian bryozoa x ), I have cndeavoured to arrange that forms in 



') Kritisk Forteckning öfver Skandinaviens Hafs-bryo:oer, Öfvers. K. Vet.-Akad. Förh. 1865 — 1867. 



