The Structure of the Mammalian Césophagus. 35 
(61) except that I did not find the striated fibres extending so far 
down. The following table shows the condition found on the pos- 
terior wall of two human cesophagi. 
No. LENGTH. | STRIATED. | MIXED. UNSTRIATED. 
. | | 
il. Longit. 21 cm. | 6.2 cm. 1.95 em. | 12.35¢em. 
Cire. | Sol neGMme 4.63 cm. 12.35cm. 
| 
| Longit. 21.3 em. | 5.6 em 2.4 em. 13.3 em. 
2. | Cire. | 3.6 em. | 4.75 em. | 12.95 cm. 
| | 
These measurements show that the unstriated fibers extend some- 
what higher in the circular coat than in the longitudinal coat, but 
that scattered striated fibers extend to about the same level in both 
coats. Approximately the lower two-thirds of the cesophagus is pro- 
vided with smooth fibres only. I did not find the striated fibres in 
the lower end of the cesophagus which have been described by Gil- 
lette (72) and Coakley (92). As Schaffer has shown, the unstri- 
ated fibres may occasionally extend in the circular coat as far as the 
lower border of the pharynx or even into the pharynx. 
GENERAL CONCLUSIONS. 
In addition to the specific data recorded in the preceding pages 
certain general conclusions may be drawn from the observations and 
from those of previous workers. 
As regards the occurrence of cesophageal glands the species exam- 
ined and those previously described may be divided into three groups: 
A. Mammals in which the esophageal glands are wholly lacking 
below the level of the cricoid cartilage. To this group belong all the 
rodents examined, including the following species :—Arctomys monax, 
Tamias striatus, Cavia, Erethizon dorsatus, Lepus cuniculus and 
Lepus nuttalli, Mus decumanus, Sciurus hudsonicus, and Geomys 
bursarius. In addition to these Sciurus vulgaris and Spermophilus 
citillus have been reported by Oppel as lacking esophageal glands. 
Here also belong the ungulate species Bos taurus, Ovis aries and 
Equus caballus, the carnivor species Felis domestica, Vespertilio 
