No. 3] LOXOSOMA DAVENPORT/. 373 



two groups have a common function from the fact that they have 

 the same histological characteristics and in life the same color. 

 The later study of sections of animals fixed by other methods 

 (Hermann's and Flemming's fluids) has led me to doubt 

 whether the space as shown in PL XXXIII, Fig. 33, around 

 the cluster of excretory cells, is normally present. The failure 

 to find it in such sections has led me to suspect that it may be 

 an artifact produced by the shrinking of the cells by reagents. 



Several questions must be left for the time undetermined. 

 I am convinced, however, that the excretory organ in this spe- 

 cies is composed chiefly of clustered vacuolated cells which are 

 not arranged in linear order and which are not pierced by an 

 intracellular canal. It will be impossible to determine the 

 structure more exactly until many more sections made from 

 animals fixed by a variety of reagents shall have been studied. 



Relation of L. Davenporti to Other Species. — That L. Daven- 

 porti is a distinct species is shown by the possession of flask 

 organs and mammary organ, structures heretofore unknown for 

 the genus, by the greater number of tentacles, and by the con- 

 dition of the foot. In these respects it differs from all other spe- 

 cies known. It resembles most closely L. crassicauda, with 

 which it corresponds in the general proportions of the parts of 

 the body, in the possession of the row of large dorsal cells, in 

 the absence of a foot-gland, and in the rapidity of asexual repro- 

 duction and the persistence of the buds. 



Material and Methods. — L. Davenporti occurs in Cotuit 

 Harbor, a tributary of Vineyard Sound, associated with the 

 annelid Clymene producta. This worm inhabits a long tube 

 extending vertically downward into the sand for more than a 

 foot and made up of sand grains cemented together. Though 

 the nearly related worm, Axiothea (" Clymenella"), lives under 

 almost exactly the same conditions and in the same sand fiat, 

 I have never succeeded in finding a specimen of Loxosoma 

 associated with it. The flat in which the worms burrow is com- 

 posed of almost pure sand and is bathed constantly by a strong 

 current of clear sea water. 



No means have been discovered for stupefying the Loxosomae 

 in an expanded condition, although a number were tried. The 



