160 PROCEEDINGS OF THE NATIONAL MUSEUM vol.84 



lar plexus of the esophagus as it is in many species, and the major 

 dorsal openings of the more posterior hearts are more directly con- 

 nected with the plexus, but the term dorso-esophageal hearts seems 

 just as appropriate and is used. 



Calciferous gland is a term applied to a kind of glandular develop- 

 ment found in the wall of certain parts of the esophagus of some 

 kinds of earthworms, including the Lumbricidae, Diplocardia^ and 

 some others. Similar organs are found in the species of Megascolides 

 and Plutellus here described. In such worms there may be one or 

 more pairs of lateral enlargements Avithin which the epithelial lining 

 of the lumen has numerous diverticula, folds, or even lamellae with 

 an abundant supply of branches of the circulatory system. In some 

 cases, especially among the Lumbricidae, small particles of calcium 

 carbonate appear in abundance in such glands. In the Lumbricidae 

 these glands are usually located in somites 10-14. In Diplocardia 

 they are found in somites 14-15, and in the different species of that 

 genus there is a notable diversity in the extent of their development. 

 In some species the folds are not very high or very numerous, while 

 in certain other species they are more numerous and crowded and 

 attain a complexity similar to that found in the Lumbricidae. A 

 similar variability in complexity is found in species of Megascolides 

 and Plutellus described in this paper. In these species the calciferous 

 glands are located in somites 9, 10, or 11 to 14, 15, or IG. 



Nephridia are lacking in a very few somites at the anterior and 

 posterior ends of worms belonging to Megascolides, as they are in 

 other kinds of North American earthworms, but instead of the 

 other somites having but one pair to each somite there are several 

 times as many nephridia to each somite in the species of Megascolides. 

 The nephridia in the anterior part of the body are all very small and 

 are known as micronephridia. In the posterior region each somite 

 with nephridia has several micronephridia and also a single pair of 

 larger ones termed meganephridia. 



Genus MEGASCOLIDES McCoy 



Megascolides McCoy, Prodromus of the zoology of Victoria, vol. 1, decade 1, p. 

 21, 1878. 

 The discovery of a species of Megascolides in North America in 

 1896 was of considerable interest because of the fact that other species 

 of the genus had been found only in the region of Australia, south- 

 eastern Asia, and neighboring areas. The discovery of several addi- 

 tional species in a limited region in North America, all of them 

 different from the known Old World species, naturally leads to the 

 assumption that the first appearance of representatives of the genus 

 in North America may have been at a time sufficiently long past 

 to have allowed the differentiation of new species since. 



