D. BRYCE ON M ACROTRACHELOUS CALLTDIN^. 439 



of the mouth opening (now conspicuous on the ventral side of the 

 corona) . The first cervical segment carries the antenna, the second 

 contains the greater part of the brain, and the third is usually 

 occupied by the mastax. These six segments are retractile within 

 those of the trunk. 



The Trunk comprises those segments whose cuticle forms the 

 exterior covering of the Callidina when most retracted. These are 

 the first, second, third, and fourth Central, the Pre-anal, and the 

 Anal. The second, third, and fourth central have the appear- 

 ance of one large segment, the limits of the third being almost 

 obliterated, and only indicated by slight undulations of the contour 

 and of the longitudinal skinfolds. The greatest width of the body 

 is usually attained in the third central, which, with the other central 

 segments, affords room for the stomach and the two ovaries. A 

 strong constriction separates the fourth central from the two 

 following segments. The pre-anal is generally of considerable bulk ; 

 it contains the intestine, and gradually narrows into the smaller 

 anal, which includes the contractile cloaca and the anus. 



The Foot comprises normally four segments, the first, second, 

 and third Joints, find the Terminal Joint, and is retractile within the 

 trunk. The third joint bears the spurs, and is the last segment 

 usually visible. In the act of taking fresh hold with the foot the 

 terminal joint is quickly and momentarily protruded from the ven- 

 tral portion of the third joint, and, being directed forwards and not 

 backwards, escapes all but the keenest observation. It carries three 

 or four toes, or in some species these are replaced by a perforate 

 disc, used like them in the aftixment of the foot. 



Of these 16 segments it is often difficult to define the first rostral 

 from the second, and the pre-anal from the anal. Frequently also 

 the appearance of four cervical segments is equally confusing. 



The food entering at the mouth is conducted by a long ciliated 

 Gullet into the cavity of the mastax,-and, passing between the rami, 

 enters the OEsophagus, and is thence forced into the Stomach, whose 

 length is slowly traversed. It is then projected into the Intestine, 

 thence into the Contractile Cloaca (see under Call, misseola), and is 

 finally expelled through the Anus. 



The two ovaries are now demonstrated to consist each of two 

 parts — a large Yolk-mass with eight (more or less) large bright 

 nuclei, and a small Germ-mass placed upon the inner side of the 

 Yolk-mass, and containing some 4 to 12 minute nuclei. 



