KONGL. SV. VET. AKADEMIENS HANDLINGAR. BAND 25. N:0 9. 5 



Although, in this way, many and various localities liave been searched, it is still not 

 to he expected, that our collections at pi-esent should afford materials enough for a some- 

 what complete synopsis and study of the fauna in (jucstion. Many a time the whole 

 niatei'ial from a locality consisted of a small quantity of sand or mud accidentally ad- 

 hering to tiie more conspicuous contents of the dredge, and only occasionally I have been 

 enabled to examine somewhat larger quantities of bottom samples. Particularly amongst 

 the Astrorhizidas and Trochamrainida;, as also in the fainily of Lagena;, we may expect 

 to find in our latitudes numerous forms not here recorded. 



In arranging the members of this fauna I have adhered to the Linnean method of dis- 

 tinguishing the species by the least tickle features wliich in every case present themselves. 

 Any other method of systematizing, aiming at an unnatural differentiation of allied forms 

 on the basis of smaller differences, results only in confused crowds of nominations of no 

 distinctive or specific value and of no benefit whatever for our study. Intermediate forms, 

 presenting unimportant differences from the typical species, I therefore range as "varieties" 

 or "allied forms" with or without distinctive denominations. 



Any one who for some length of time has been engaged in the study of this class, 

 is familiar with the common occurrence of even great diversity between individuals appa- 

 rently issued from the same stock. Whenever this is the case we should not be too 

 prone to dissociate such forms under different denominations, the more so as it may be 

 expected that the employed 'characters" are not avaOable for a satisfactory limitation of 

 more validity than what concerns local and individual minor discrepances. Thus, in syste- 

 matizing this class, it is not at all needed to rank "varieties" as "species", as has been 

 insisted upon by Buady. Although it would be consistent with nature to speak of 

 "variety of variety", we are not compelled to carry out such a scheme, when we coordi- 

 nate all varieties under their type species. It is neither easier nor more difficult to cha- 

 racterise distinct species amongst an assemblage of forms of this class than is the case 

 within other classes of organisms, particularly when we have to deal with allied forms 

 extending over several geological horizons or areas of the sea. Intermediate forms and 

 varieties are met with at every instance, and this course of things will always bring 

 about a more or less deficient limitation of species and genus, but by giving the notion 

 of species its due compass, and expanding the spheres of genera, always selecting the 

 more constant differential features, we may overcome a good deal embarassing incon- 

 sistences in the system, the chief purpose of which should be to unfold the affinity and 

 origin of the forms. 



A discrepance in the features of forms issued from the same stock, is not seldom 

 met with in this class, and this kind of variation has brought about and still causes a 

 great deal of confusion in systematizing. It evidently arises from the various degree 

 of development of the initial segment or primordial embryochamber which is subject 

 to some variation in the same species or even in the same individual or "colony". 

 This variableness seems to concern not only the size but also the power of growth of 

 the embryo-chamber, and results in modifications of the arrangement of the subsequent 

 segments. 



