38 STROBILOPS, MEXICO, CENTRAL AMERICA. 



Helix salvini Tristram, Proc. Zool. Soc. London, 1863, p. 

 411. — Pfeipfer, Monogr. V, p. 334. — Strohila salvini von 

 JVLvRTENS, Biol. Centr.-Amer., Moll., p. 174, pi. 10, f. 1-lc. 



I have not seen this species, which appears to be more ele- 

 vated and more distinctly angular than 8. strebeli, with a 

 •vsdder umbilicus than any North American species of its group. 

 The measurements given by von Martens from the type do not 

 agree well with his figures, and are given differently in his 

 table (Biologia, p. 173), perhaps partly transposed with those 

 of 8. labyrinthica. According to his figure, the umbilicus is 

 contained about 3.7 times in the diameter. Von Martens 

 writes as follows : 



" An inspection of the typical specimens, kindly lent me 

 by Canon H. B. Tristram, enables me to give a fuller de- 

 scription of this species, which proves to be nearly allied to 

 8. labyrinthica (Say). The riblets of the upper surface cross 

 the angle of the periphery and extend a little way on the 

 lower face of the shell. The umbilicus occupies about one- 

 third of the diameter of the shell, whereas in 8. lahyriiithica 

 it occupies only about one-fifth of it. 



' ' The internal lamellae are in this species about the same as 

 in 8. lahyrintliica, according to the description given by E. 

 Morse and the figures contained in Binney's works. Two 

 whitish spiral lamellae are visible from outside at the base, 

 shining through the shell, more distinctly in young shells than 

 in full-grown ones, because in those the shell is thinner; they 

 are situated really on the upper side of the lower wall of the 

 last whorl. Two others, situated on the lower side of the 

 upper wall or ceiling (parietal lamellae), are to be seen by 

 looking into the aperture of a not full-grown shell ; the upper- 

 most, or that nearest the suture, is the longest, extending 

 even somewhat beyond the limit of the aperture in the ob- 

 served specimen, the following one is shorter and lies more 

 beneath — it corresponds to the third of 8. labyrinthica in the 

 above-mentioned figures. A corresponding lamella to the 

 second of 8. labyrinthica is not visible in the specimens of 8. 

 salvini, probably only because it does not come so near to the 

 aperture, and I would not break the only shell which exhibited 



