8 BULLETIN 71, UNITED STATES NATIONAL MUSEUM. 



LAGENA SACCULTTS Fornasinl. 

 Plate 3, figs. 1-3. 



Lagena acuta H. B. Brady, Bep. Voy. Challenger, Zoology, vol. 9, 1884, p. 474, 



pi. 59, figs. 6a, b (not L. acuta (Beuss)). 

 Lagena acuta, var. sacculus Fornasini, Mem. Accad. Sci. 1st. Bologna, ser. 5, vol. 9, 



1901, p. 49, fig. 3. 



Description. — Test usually somewhat carinate, body of test in 

 front view nearly circular, in end view broadly elliptical, neck some- 

 what variable in length and breadth, but varying correspondingly 

 with the development of the carina, which may be very slight or 

 rather well developed according to the specimen; wall smooth, 

 fairly thick, either transparent and distinctly punctate or thickened 

 and nearly opaque, aboral end of test extending out into an acute 

 angled process; aperture at the exterior elongate, elliptical, with a 

 well-developed entosolenian neck extending well into the central 

 cavity of the test, usually with the inner end somewhat expanded, 

 carina when well developed often showing radial lines formed by 

 punctse extending in from its periphery. 



Length up to 0.6 mm. 



Distribution. — Well distributed in the Nero material from the region 

 west of the Hawaiian Islands to Guam and the coast of Japan. The 

 depths of the stations at which this species was taken vary from 

 1,088 to 2,225 fathoms, most of the stations being more than 1,500 

 fathoms in depth. There are records for two Challenger stations, 241 

 in 2,300 fathoms and 244 in 1,850 fathoms, both east from Japan. 



This is one of the species in which a definite variation seems to 

 occur. In the specimen figured by Fornasini there is little if any 

 keel developed and the external neck is very short and broad. From 

 this the variation is through a series increasing the breadth of the 

 carina and at the same time increasing the length of the neck until 

 in such specimens as that figured by Brady and again in my figure 

 (fig. 3) there is a broad fairly thin keel and a relatively long netfk. 

 Throughout the series, however, there is the same shape to the body 

 of the test, circular in front view and broadly elliptical in end view; 

 the external aperture remains elliptical and the entosolenian neck of 

 the same general shape and of fairly uniform length. 



Reuss's figure of Fissurina acuta shows a specimen with a much more 

 elongate body and an acute apertural end, the whole outline con- 

 siderably different from our recent specimens, and apparently Forna- 

 sini is right in segregating this form from that described by Reuss. 

 Even Brady questioned the identity of the two. 



