322 EDWARD S. MORSE ON 



In examining a large number of the shells of L. anatina I found a certain proportion 

 of them thickened, discolored, and eroded, forming a marked contrast to the other 

 specimens equally large with clear green shells, thinner in texture and more perfect in 

 condition. As all the specimens examined were collected at the same time in July, one 

 might infer that the rougher, thicker shells belong to a last year's growth, and it is 

 therefore possible that this species may live two or more years. In an individual of an 

 undetermined species of Lingula, dredged in Nagasaki Bay, Japan, the dorsal shell was 

 somewhat pointed, while the lower shell was evenly rounded in front and minutely 

 notched in the median line (46 : 8) . This may be, however, only an individual variation. 



The shell of L. lepidula is much more transparent than that of Glottidia and for this 

 reason I was enabled to make out more of the internal structure, circulation, etc. In the 

 smaller individuals the shell is steel-gray, or light bluish white ; in the larger specimens 

 a tinge of green is seen. In alcohol, these colors change to a imiform light yellowish. 



In 42 : 3, a drawing is given of the peduncular end of L. lepidula. Here the pedun- 

 cular opening is flaring and reminds one of the early brachiopods figured by HaU and 

 others. A direct end view shows the straight, horizontal lines of accretion so often 

 depicted in the Cambrian forms. The protegulum is oblong-ovate, the posterior margin 

 being straight ; the periphery of this stage is distinctly yellowish in color, and this is of 

 interest as marking a distinct period in the shell growth. In the ventral shell the out- 

 Hnes of this early stage may often be detected in mature specimens. The dorsal shell is 

 more pointed and shows a conspicuous, well-shouldered foramen. The successive incre- 

 ments of growth are seen in blunt, tumid beaks imposed one after another on the area 

 covered by the protegulum (42: 3,4,7). In one specimen was observed a curious 

 alation projecting on each side of the protegulum area, the result of some thickening due 

 to the peduncular attachment (42 : 8) . 



In Glottidia, the protegulum, while showing a straight posterior margin with a slight 

 shoulder as it connects with the subsequent growth, is circular in outhne ; as in Disci- 

 nisca, the periphery of this circular stage is minutely indented and radially striated 

 (42: 2). Brooks (78) has shown, in the free-swimming stage of this species, the same 

 straight posterior margin with projecting points at either end. In a species of Lingula 

 collected in Nagasaki the protegulum is ovate with the same straight posterior margin 

 (61: 1)- In aU these instances, the peduncle is firmly adherent to the ventral shell, the 

 beak of the dorsal shell standing free with an interspace between it and the peduncle. 



In Discinisca lamellosa, the protegulum is elongate-ovate with anterior and posterior 

 margins equally rounded. A perfectly circular nucleus is outUned in the posterior half of 

 this stage (42: 12) . This circular nucleus is made up of polygonal cells, and the irregular 

 fracture of the edge shows that there have been no regular increments of growth. In this 



