402 PEOCEEDINGS OF UNITED STATES NATIONAL MUSEUM. [1885. 



from the anterior extremity to the rim of the bell surrounding the open- 

 ing into the bell cavity, where they are extended into projections more 

 or less markedly serrated. In addition to these three longitudinal 

 ridges there is on the posterior side of the largest a thin plate serrated 

 at its lower edge, which forms as in A. pentagona a longitudinal sheath 

 into which the axis can be withdrawn. When the bell is placed on one 

 side, so that the anterior conical end of the bell is at the right hand 

 side, the largest elevation will be seen above and the smaller below, 

 while the serrated covering-plate lies between and parallel with the 

 larger ridge. The margin of the larger ridge seen in this way is rounded 

 and has two ridges, or is double for a short distance near the junction 

 with the bell margin, or where it forms a projection. It gradually be- 

 comes reduced in elevation, passing from the posterior to the anterior 

 extremity of the bell, and is more rounded posteriorly. The other 

 elevations are slighter with indistinct serration on the crest. The 

 covering-plate lies between the largest and the smallest. The section 

 of the posterior nectocalyx which lies betw^een them is the posterior face 

 of the distal or posterior nectocalyx. 



The internal organs are in too imperfect a condition for study. In 

 the cavity of the somatocystthe remains of the " spongy" mass of cells 

 were observed. The walls of the cavities of both anterior and posterior 

 nectocalyces have become so "shrunken that the course of the tubes 

 could not be observed. 



The stem and its appendages are broken off and are not found with 

 the nectocalyces. This species resembles A. trigona Q. and G. more 

 closely than it does the specimen described as A. trigona by Huxley. 

 Minor differences from both do not warrant my redescribing it as a new 

 species. 



Family HIPPOPODID^. 



Gleba hippopus, Forskai. 



Specimens examined. 



This specimen is a single nectocalyx. 



