LIVING BRACHIOPODA. 317 



dula in Jaj^an, it was some time before I discovered that it was uot even generically iden- 

 tical with the form now nnder consideration. Aside from the internal strncture of the 

 dorsal and ventral shell, the form of the protegulum, the presence of gill ampullae, the 

 arrangement of the oblique muscles, and the more anterior position of the coelomic cavity, 

 I found that in Glottidia the setal tubes were not formed, though the lateral setae assume 

 a vertical position when partially buried in the sand, as in L. lepldula ; the sand tube is 

 much more complete and symmetrical and in alc(jhol is retained on the peduncle, while in 

 L. lejyUhda the sand tube becomes detached. In general behavior, however, the two 

 forms are almost precisely alike. Charles Schuchert ('97), in considering the enormous 

 period in geological history occupied by the Lingulidae, says that the only change observ- 

 able is that in the ancient forms the viscera occupy a little more and the In-achia a some- 

 what less space than in the later forms. Glottidia by these characters is a more ancient 

 type. This same feature in tiie relative space occupied by the two regions is seen in the 

 adolescent state of Discinisca as compared with the mature state. 



When an individual was placed on the sand it would slowly throw its peduncle into a 

 series of irregular convohitions ; directly the dorsal shell would be set in motion, oscillat- 

 ing from side to side in a peculiar rotaiy and sliding manner, and during this action the 

 shells were rather close together but not entirely closed, the fringes of lateral setae were 

 moving in a peculiar rhythm, not swinging Ijack and forth simultaneously, l)ut the 

 impulse would start posteriorly and move forward; the posterior Inuiches of setae would 

 swing widely back and forth ; the setae, on account of their minute longitudinal markings, 

 would appear a somewhat iridescent steel-blue. The sand by these efforts would be 

 gathered in an irregular ridge and sometimes would adhere by the mucus which is freely 

 emitted, so that when the animal was lifted from the water a narrow and irregular ribbon 

 of sand would be found encircling the creature. In some cases, the posterior half of the 

 body Avould be encased in a continuous sand sheath (41: 1-t). In one specimen, in which 

 the peduncle was broken close to the l^ody, the creature was observed to move sideways 

 to the distance of an inch or more, piling up the sand in a ridge as it moved along 

 (41: 12). It then began burying itself in the sand, going down head first, using the 

 anterior portion of the shells in a shoveling motion and finally disappearing. Tlie next 

 day it was found affixed to the bottom of the bowl by the peduncular end, though not 

 attached by the peduncle. It had made a sand case adhering to the IjowI and this case 

 enclosed the lower lialf of the body. Another individual traveled a distance of two 

 inches on one side of its body, the setae plowing into the sand and forcing the body for- 

 ward; other specimens penetrated the sand by means of the peduncle and, in a vermiform 

 way, dragged the body out of sight. When at rest, the body would )je half out of its bur- 

 row, the shells partially open and the lateral setae standing vertical and meeting at their 



