384 TERRESTRIAL AIR-BREATHING MOLLUSKS. 



Spurious Species, etc., of Cylindrella. 



Oylindrella pontijica, Gould, ia Macroceraynus Kieneri, Pfk. 



Cylindrella Goldfussi and Koetneri are species of Ilulospira. 



Cylindrella campanulata of Terr. Moll. U.S., I. 109, ia unknown to mc. 



MACROCERAMUS, Guild. 



Animal as in Cylindrella (q. v.) See also below under M. Kieneri. 

 Shell turreted or lengthened-conic, rimate; wliorls 9-15, gradually increas- 

 ing, the last often angular ; aperture round, short, columella usually plicate ; 

 peristome expanded, its margins subequal, subparallel, not continuous, the ex- 

 ternal arched, the columellar dilated, reflected. 



Jaw thin, almost membranous, serai-transparent, light horn-colored, strongly 

 arched, ends acuminated ; cutting margin without median 

 ^'^ ttoIL projection ; anterior surface with numerous delicate, sepa- 



rated ribs, denticulating both margins; these ribs run 

 obliquely towards the median line of the jaw, so that the 

 central ribs meet before reaching the lower margin of the 

 jaw, forming an upper median triangular space between 

 the ribs. 



It was formerly considered that this jaw was actually 

 in separate pieces, whose overlapping margins formed the 

 ribs upon the anterior surface (see Fig. 267). More careful 

 examination, however, has proved the jaw to be in one sin- 

 gle piece, with delicate ribs upon its surface. 

 Jaw of There arc over 50 ribs on the law of the only one of 



M. signatus (Bland). •' . _ . 



our species I have examined, M. Gossei. I give a copy 

 of Mr. Bland's figure of the jaw of M. signatus, which is similar. 



The lino-ual membrane of Macroceramus was supposed to be the same as in 

 Cylindrella described above, as that of M. signatus was so found by Mr. Bland 

 (Ann. Lye. Nat. Hist. N. Y., VIII. 162), and Crosse and Fischer (Joiu-n. de 

 Conch., 1870, PI. Ill Figs. 14-16). It was, therefore, with surprise that I 

 found an entirely different type of dentition in M. Gossei. I can in this place 

 only note the difference, and leave to future study the question of its bearing 

 on the generic position of the species. 



M. Gossei (PI. X. Fig. Q) has a membrane very long and narrow ; teeth 

 about 40 — 1 — 40, in scarcely oblique transverse rows, decidedly not en chevron. 

 Centrals with a long, narrow base of attachment with somewhat expanded 

 lower lateral angles, its upper margin squarely reflected. The reflected por- 

 tion is very small, and bears three short, blunt cusps, the median the largest, 

 all three with distinct cutting points. The base of attachment of the laterals 

 is long and narrow, its outer lower angle irregularly cut away ; the upper 

 marcrin broadly and obliquely reflected, the reflected portion thrown off ob- 



