698 PROCEEDINGS OF THE NATIONAL MUSEUM. vol. xxxiii. 



the results of my labor, I found myself the possessor of 29 fine Phiv- 

 orhis. These Avere carefully packed in Spanish moss to prevent in- 

 juring; their delicate edges and taken to the hotel. The following- day 

 was spent in further searching;, and ended by increasing the number 

 of specimens found to 40. 



INIost of the specimens of Piano /'his inogni-ficvs found Avere attached 

 to the underside of the expanded leaves of the larger species of the 

 white pond lily, probably a Castalia^ though many were obtained 

 from the heavy banks of Potamogeton growing in dense masses a 

 short distance offshore. By pulling these masses and shaking them 

 the mollusks were dislodged and rose to the surface for a moment 

 before sinking to the bottom. I was able to find tliem only along the 

 border of the south side of the lake, the shore line of which consists 

 of a series of loops, and then only off the west side of the extreme 

 points of each loop. It is quite possible that the shells live in greater 

 numbers in deeper parts of tlie lake, and that they are driven insliore 

 with dislodged vegetation by northwest winds. (See Plate LVII, 

 figs. T-0.) 



Other lakes about Wilmington, as w-ell as the river, were explored 

 during my visit, but none yielded this large shell nor the new species 

 described below, which so far confines the distribution of the two to 

 this lake. 



There are many interesting features about the very jirofuse mol- 

 luscan life of this lake. I found among other fornis a neAV Liogyra 

 and probably also a new Limosina^ the latter, I believe to be the most 

 northern record for that genus. I observed also a curious habit of 

 the white pond lily of forming a circlet of fleshy roots on the stem, 

 about a foot below the expanded leaves. Many of these were floating 

 free near the edge of the pond, where they undoubtedly become 

 anchored and start a new plant by this natural slipping process. 



The specimens collected were brought home alive ; some were pre- 

 served in alcohol, but the greater number were placed in aquaria, 

 where it was soon discovered that Planorhis magnifici/s had other 

 interesting features besides being our largest form. They were 

 entirely blind. Xot one of the lot showed even the trace of an eye. 

 Ivudiments' of this organ, however, may be seen in miscroscopic sec- 

 tions. Avhere it appears as if it had been covered by the thickened 

 cuticle. 



I was anxious to note if the species w^ould reproduce itself in cap- 

 tivity. Up to June 15, 1907, when I left on my vacation, this had not 

 taken place. Large appetite, slow growth, and a great mortality 

 sum up the events to that time. The mortality appears to have con- 

 tinued until only a few of the mollusks remained. When I returned 

 to Washington in September and examined the aquaria, I found 

 several young specimens of one and a half wdiorls which had been 



