THE NAUTILUS. 15 



any sculpturing. The whole disc is densely and heavily sulcate, 

 nacre white, salmon or purple. Teeth strong ; cardinals double in 

 both valves ; laterals single in the right valve, cicatrices well 

 marked, confluent behind, separate before. Beak cavities rather 

 shallow. 



Dr. Ortmann writes that the anatomy is practically that of the 

 Elliptio division of Unionidas : Marsupium in the outer gills, glo- 

 chidia subcircular ; length 0.23, alt. 0.22 mm., about like gibbosus 

 Barnes. Gravid in February. The sexes may not be indicated by 

 any dimorphism. Found by Mr. A. A. Hinkley, in the Conchins 

 River, near Quirigua, Guatemala (Atlantic drainage). Cotypes 

 have been generously distributed by Mr. Hinkley to the Academy of 

 Natural Sciences of Philadelphia, the U. S. National Museum and 

 various collectors cabinets. 



This shell is clearly placed in the Nephronaias division by its 

 evident near kinship to melleus Lea, and to persulcatus Lea, from 

 which species ortmanni differs in being much larger, and of a differ- 

 ent outline. 



Some specimens resemble in shape U. goascoranensis Lea, and U. 

 sphenorhynchus Crosse and Fischer, but these species are not sulcate. 

 The anatomy of this shell being that of Elliptio makes it necessary 

 for the systematist to recast his ideas of Nephronaias, hitherto sup- 

 posed to be allied to the Lampsilince. It is with great pleasure that 

 I dedicate this species to my friend, Dr. A. E. Ortmann. 



Mr. Hinkley procured also numbers of the Unio calamitarum 

 Morelet, from a mountain stream, " Rio Blanco," whose mouth lies 

 opposite Livingston. 



The stones rolling down the stream after the tropical rains play 

 havoc with the Unios, ninety per cent, having met with accidents. 

 Consequently, the outlines of the shells are extremely variable. Mr. 

 Lea made the error of spelling the name calimatarum, pointed out 

 by von Martens, who supposes Morelet's name to mean either " the 

 Unio of a little green frog," or "of reeds" (as also Sowerby). 

 These shells of Hinkley's show that Morelet may have intended that 

 his U. calamitarum should mean " the unio of calamities " (from 

 calamitas^), but if so it is rather peculiarly constructed. The syn- 

 onymy of this shell includes the U- dysoni Lea, and [7. lijalmarsoni 

 Dunker, possibly others. 



A plate illustrating U. ortmanni will appear next month. 



