444 D. BRYCE ON MACROTRACHELOUS CALLIDINJE. 



bear four dorsal and two ventral knob-like prominences arranged in 

 two sets of three. On the ventral side the pair there visible are 

 widely separated, the intervening margin of the segment being 

 excised in a moderate curve. When the Callidina is feeding the 

 neck is so withdrawn by retraction that the exterior of the under- 

 lip rests upon this excised margin. On the dorsal side the interval 

 between the second and third prominence is greater than that 

 between the first and second or the third and fourth. When the 

 animal contracts itself, and the invertile segments are drawn back 

 within the trunk segments in the usual way, these six prominences 

 become the anterior of the irregularly globose figure which results, 

 and in the process each set of three is so gathered together, while 

 remaining relatively apart from the other set, that the produced 

 anterior extremity of the contracted animal seems to have a median 

 cleft, an appearance I have not observed in any other species. 



The transverse skin-folds do not extend quite across the ventral 

 surface. When this is directly visible there are conspicuous at 

 each side two longitudinal folds, properly belonging to the lateral 

 series, and more centrally three very short folds. The central one 

 extends only from near the edge of the first central segment where 

 most excised to the posterior of the same segment, but not reach- 

 ing the first transverse fold. The pair next to it are but little 

 longer. Starting near the tips of the ventral prominences already 

 mentioned, they extend to the first transverse fold. These three 

 short skin-folds are not included in the stated fourteen dorsal and 

 lateral folds. The next pair are much longer, and proceed from 

 the tips of the prominences to near the rear of the fourth trunk 

 segment, describing each a curve in their course (like the brackets 

 of a parenthesis). The third pair arise from between the ventral 

 prominences and the outer dorsal prominences, and proceed to the 

 rear of the pre-anal segment. In like manner the transverse folds 

 have various lengths and courses. The first and second belong to the 

 second central, the next throe to the third, and the following three 

 to the fourth. None of these eight mark the limits of segments, 

 but the ninth and a faintly- marked tenth are plainly the posterior 

 edges of the fonrth central and the prc-anal segment. Of the first 

 eight only Nos. 4, 5, and 6 reach the inner longer pair of longi- 

 tudinal folds. Kos. 7 and 8 turn towards each other, and become 

 continuous. It is usual to refer to that part of the foot which is 

 protruded beyond the spur-bearing segment as consisting of a 



