6 PROF. ALLMAN ON THE 



The ovaries, according to Vogt, occupy in the female exactly 

 the same position as the testes in the male. The ova are expelled 

 from them one after the other, and pass into the vestibule, which 

 may become loaded with them. Here they run through certain 

 early stages of development, and are ultimately expelled as ciliated 

 larvae. 



One can scarcely overlook the close correspondence between 

 the organs here described by Vogt as ovaries and testes and those 

 which Salensky describes as a glandular apparatus with a probable 

 excretory function. 



Loxosoma is regarded by Vogt as an archetypal form, from which 

 that of the ordinary Polyzoa has been derived by successive modi- 

 fications. 



II. Hypophorella expansa. 



We are indebted to Ehlers for a valuable memoir on a very 

 remarkable burrowing polyzoon, to which he gives the name of 

 HypopJiorella expansa*. 



He met with it on the coast of Spickeroog, where it occurred 

 in burrows which it had formed in the thickness of the tube- wall 

 of Terebella conchilega. The completely developed colony is com- 

 posed of two kinds of dissimilar members or zooids. Of these the 

 one set is destitute of intestinal canal, and is capable of only non- 

 sexual reproduction, while the other hasadeveloped intestinal tract, 

 as w r ell as sexual organs which give rise to fertile eggs, non-sexual 

 reproduction occurring here only exceptionally. The intestineless 

 members have the shape of long thin threads ; he designates them 

 as " Stengelthiere." The intestine-bearing members are urn- 

 shaped, or flask-shaped, and are called by Ehlers " Nahrthiere." 



The filiform zooids, or " Stengelglieder," form stolons by which 

 the colony extends itself, and on which the nutritive zooids or 

 " Nahrthiere " are borne. The starting-point of the entire colony 

 is a thread-like Stengelglied, which is developed from the larva. 

 From the distal or growing end of this are produced in linear 

 order a succession of similar filiform zooids, which together form 

 a progressive filament, which burrows between the layers of the 

 Terebella-tube . The distal end of this tilament thus represents 

 the youngest, as yet undeveloped filiform zooid. 



From the single members (Glieder) of this long filiform stolon 



* E. Ehlers. ''Hi/pophorella expausa, ein Beitrng zur Kenntnissder minenden 

 Poryzoa,'' Abhandl. der konigl. Gesellsch. der Wissenschaften, 1876. 



