CRICK : ON PLEURONAUTILUS PULCHER, N.SP. 17 



nepionic stage of the shell is preserved as an internal cast ; it 

 was not free, but abutted against the succeeding whorl ; the test is 

 wanting on its peripheral and lateral areas, but a fragment, with its 

 characteristic sculpture, is preserved on the dorsal area, though the 

 greater part of this area is concealed by matrix, which likewise 

 obstructs the end view of the ananepionic substage. There are, how- 

 ever, on the peripheral part of the tip of the internal cast of the first 

 chamber indications of a vertical cicatrix. Even in the nepionic stage 

 the cross-section of the whorl is depressed elliptical, a form which is 

 maintained up to the base of the body-chamber. The siphuncle in 

 the neanic stage, just before the end of the first whorl, is at about 

 tu'o-fifths of the diameter from the periphery, a position which it 

 also occupies at the last septum, thus maintaining the same position 

 in all stages of growth. The sculpture of the test of the ephebic stage 

 is particularly well shown. The form of the muscular attachment is 

 also displayed. On each side close to the base of the body-chamber 

 there is a transverse semi-oval area, having its greatest height, 3 mm., 

 at the lateral boundary of the lateral ventral zone ; its broad ventral 

 end, situated on the peripheral boundary of the same zone, is connected 

 with the ai'ea on the opposite side by an exceedingly narrow band 

 immediately above the last septum ; dorsally each area gradually 

 diminishes in width as far as the umbilical shoulder, i.e. for a distance 

 of about 7 mm., whence it passes as a narrow band, somewhat wider 

 than the ventral band and adjoining the edge of the last septum, 

 across the suture of the shell or ' line of involution,' and over one-fourth 

 of the width of the impressed zone, the rest of its course on the 

 impressed zone being obscured by a film of the test. The semi-oval 

 area on each side and the dorsal band are minutely punctated ; the 

 ventral band is so excessively narrow that it is difficult to say whether 

 it is punctate or not, but puncturation appears to be lacking. The 

 semi-oval area on one side bears two small pieces of shellv matter, the 

 surface of which is also punctate. The form of the muscular attachment 

 closely resembles that of Vestinautilus cari^iifenis (see accompanying 

 figures). This specimen also shows the character of the epidermids. 

 It belonged to the collection of the late J. W. Davis, of Halifax ; the 

 precise locality whence it was obtained has not been recorded, but 

 the matrix agrees with that of the other examples which are from 

 Hebden Bridge. 



The smaller example in the British Museum collection (jS^o. C. 213) 

 belongs to the Gilbertson Collection, but in this case also the locality 

 has not been recorded. It is 25mm. in diameter; the inner whorl 

 is fairly well preserved ; the last third of the outer whorl is occupied 

 by the body-chamber, but the greater part of this is imperfect both 

 laterally and ventrally, so that the dimensions of the specimen can 

 be best taken at a diameter of 21-5 mm. It exhibits very well the 

 sculpture of the nepionic and neanic stages, and the suture-line in 

 the ephebic stage. 



The fragment in the J^ational collection (No. C. 8631) is about 

 10 mm. long, and consists of the internal cast of the posterior portion 

 of the body-chamber and of the t\vo preceding cameroe ; it is terminated 



VOL. VI. MARCH, 1904. 2 



