160 PROCEEDINGS OF THE ACADEMY OF 
I may here mention that Tryon (Am. Jour. Conch., II. 246) 
erroneously includes in Macrocyclis a true species of Zoniies, Z. 
Hlliotti, characterized by caudal mucous pore, parallel longitudinal 
furrows above the margin of the foot, and the presence of perfect 
lateral teeth. : 
The side teeth of Macrocyctis at first sight, especially when 
seen from below, appear to be of the purely aculeate type, as the 
marginals in Zonites and Limax. From this, one is inclined to 
consider them all as marginals, and to declare that no true lateral 
teeth exist, thus making Macrocyclis to agree with Glandina in 
this particular also. A more careful study shows us that the 
teeth nearest the median line are modified from the aculeate type, 
though they do not have the distinct form of the laterals of Zo- 
nites, with decided cusps and cutting points. They seem rather 
to represent those teeth of Zonites which show the transition from 
the laterals to the marginals (see pl. II., fig. 2, the second lateral 
tooth of Z. levigatus). It may be said, therefore, that the lateral 
teeth are entirely wanting in Macrocyclis, the first side teeth 
being laterals in the transition state, the balance being pure mar- 
ginals. (See, however, J. euspira, below, which has a lingual 
membrane of Glandina.) The base of attachment of these tran- 
sition teeth is like those of the marginals, i. e., sole-like, except 
that the lower lateral expansions are more developed and angular, 
and in concava and Voyana the lower edge is excurved rather 
than incurved. The cusps are long and slender, lengthened into 
cutting points; the teeth are unsymmetrical by the greater de- 
velopment of the outer subobsolete side cusps, both of these cusps 
being distinctly indicated by expansion. In J. Vancouverensis 
there is apparently a small sharp side point on the inner side of | 
the cusp. I am not certain of its character, and have not ven- 
tured to figure it, excepting on the second tooth in fig. 4a. This 
process is seen on the first six teeth only. The balance of the 
teeth beyond the transition teeth in all the species are marginals 
of the pure aculeate type. They vary in sharpness in different 
parts of the same membrane, as will be seen by comparing my 
figure 4b of M. Vancouverensis with the marginals in profile given 
by Morse (see above fig. 2). In M. Duranti the extreme mar- 
ginals are large in comparison with those of the other species. 
In studying my figures, it must be remembered that fig. 3a, 5a, 
and 4¢ are drawn as seen from above, to show the form of the 
