MUSEUM OF COMPARATIVE ZOOLOGY. 201 



.Habitat. Stations 290, Barbados, 73 fms. ; 232, St. Vincent, 88 fms.; 155, 

 Montserrat, 88 fms. ; 253, Grenada, 92 fms. ; 273, Barbados, coral and shells, 

 103 fms. ; 45, in Lat. 25° 33' N., and Lon. 84° 21' W. Gr., 101 fms.; 177, 

 Dominica, sand and shells, 118 fms. ; 157, Montserrat, sand and stones, 120 

 fms. ; 297, Barbados, stones, 123 fms. ; 258 and 254, Grenada, 159 and 164 

 fms. ; 193, Martinique, 169 fms. ; 291, Barbados, 200 fms. ; 139, Santa Cruz, 

 sand and gravel, 218 fms. ; 147, St. Kitts, 250 fms. Its location, therefore, 

 appears to be between seventy and two hundred and fifty fathoms, in water 

 varying from 51°.0 to 69°.0 Fahrenheit in temperature. 



The relations of this form appear to be with T. vitrea, T. cuhensis, T. sphe- 

 noidea, and T. scillm. Its assemblage of characters does not appear to be shared 

 by any of those forms. The rather large number of specimens of all ages, col- 

 lected as above, show its range of variation very well. Those who would unite 

 all the above-mentioned species under one name, would doubtless include the 

 present form within that limit, and logically so. I do not see my way clear, 

 however, whatever may be thought to be the value of a " species," to ignore 

 what appear to be constant diflferences in the organisms under consideration. 

 It is probable that there are too many specific names in the group of Terebra- 

 tvla of which T. vitrea is an example, a number of additions having been re- 

 cently made to the list. The present form is certainly more difi"erentiated 

 from either vitrea or cuhensis than several which have been named and are 

 generally accepted. The form of the loop resembles closely that of T. siracu- 

 sana Seguenza (Bull. Malac. Ital., IV., tab. 4, fig. 13), its general form is more 

 like T. scillcB Seg. (1. c, tab. 3, fig. 8), at least like the variety mentioned. 

 Other discriminating characters may be found mentioned in the preceding 

 description, which, with the figures, will be a sufficient means for identification. 

 The anterior flexuosity is often, though not usually, as strong relatively in the 

 young as in the adult. The appressed neural apex is very constant. 



Terebratula incerta Davidson. 

 Megerlia incerta Davidson, Challenger Brach., p. 49, pi. xi. figs. 17, 18, 1880. 



Plate TI. Figs. 6, 6 a. 



Habitat. Challenger Expedition, Mid- Atlantic, Lat. 1° 47' N., Lon. 24° 26' 

 W., 1850 fathoms. Blake Expedition, Stations 235 and 236, in 1507 and 1591 

 fms., oozy bottom, off Bequia, bottom temperature 39°.0 F. ; and Station 16, 

 292 fms., off Morro Light, Havana, Cuba, bottom temperature 55°. 6 F., one 

 specimen only. 



This species was obtained of adult size at the stations cited. It is readily 

 recognizable from Mr. Davidson's excellent figures (by his kindness I com- 

 pared specimens) and the peculiar and characteristic radiating filaments which 

 surround the base of the peduncle. In all the specimens examined the loop is 

 incomplete, or rather the crura are not Timted. but the soft parts, the setse, and 



