18/9.] TRACHEA OF THE GALLING. 363 



as a short distance posteriorly into the middle of the lower horder 

 of the penultimate ring, from the fair-sized bony pessulus. The last 

 tracheal ring sends downwards a thick short process from its hinder 

 end on either side, to articulate with the equally developed upturned 

 posterior extremity of the first bronchial semiring, the anterior 

 upward- and inward-directed terminal limb of which is propor- 

 tionately long, at the same time that the angle it makes with the 

 main element of the ring is very abrupt. The second semiring is 

 nearly in contact superiorly with the first throughout its length. 

 Anteriorly it ends in a point, as do the lower semirings, which 

 extends a short distance into the inner membranous wall of the 

 bronchus. Posteriorly it is slightly enlarged and rounded, ceasing 

 a short distance outside the posterior angle of the semiring above, 

 with which it is in contact. 



Turning to the genus Euplocamus, in Euplocamus sioinhoii the 

 last four tracheal rings become slightly enlarged from above down- 

 wards. Between the simple antepenultimate ring aud the one above 

 it there is a slight interval, except in the middle line behind, where 

 a general fusion of the last three rings occurs, as in all Euplocami. 

 The penultimate ring sends downwards a narrow tongue-shaped 

 median process anteriorly, which touches, but does not join, the upper 

 margin of the there indented terminal tracheal ring. Its upper mar- 

 gin is also slightly irregular. The last ring is peculiar in front. 

 Besides the shallow and broad concavity in the middle of its upper 

 border, it sends downwards a deep and transversely considerable semi- 

 ovoid process, notched at its apex, which is lowermost, to form the 

 median element of the actual bifurcation of the tube. On either side 

 of this notch, just beyond it, the anterior extremity of the first bron- 

 chial semiring articulates by its triangularly expanded end, the lower 

 angle of which is jointed with the not m uch specialized second semiring, 

 which posteriorly articulates by its somewhat expanded termination 

 with the first semiring also. The hinder extremity of the first semi- 

 ring fuses with the last tracheal, as does the posterior termination of 

 the pessulus, to form a continuous cartilage along the back of the 

 tube as high as the upper border of the antepenultimate tracheal 

 ring. Antero-laterally the annular interval between the penultimate 

 and last rings is well developed, and bent downwards near the middle 

 line on account of the presence of the process and notch above de- 

 scribed. The interval between the last tracheal ring and the first 

 bronchial semiring is very large and deep on account of the great 

 size of the descending process of the former. The interval between 

 the first and second semirings is ovate and slightly deeper than those 

 which follow. The pessulus is narrow. 



Euplocamus preelatus, E. nychthemerus, and E. albocristatus 

 differ from E. swinhoii in that anteriorly the median process from 

 the lower border of the penultimate ring blends with the upper horder 

 of the last tracheal, as does the upper border, but by a more slender 

 isthmus, with the antepenultimate. In E. nychthemerus and E. albo- 

 cristatus there is a further fusion of the anterior extremity of the 



