LIVING BRACHIOPODA. 365 



IS seen just below the nephrostome ; it then widens into a thick body and continuing for half 

 the entire length of the nephridium turns abruptly upon itself, tapers slightly, and pierces 

 the anterior wall obliquely, ending in a wide, simple opening more nearly resembling the 

 exterior openings in L. lepidula or Discinisca, and in no way resembling Terebratiilina 

 (55: 8) . At 55 : 7, is another drawing showing the attitude of the nephridia in relation to 

 the body. In Dalliua grayii, the nephrostomes are united by a band and are so close 

 together as to be almost in contact (56 : 8) . The plane of the nephrostome is only sHghtly 

 inclined to the longitudinal axis of the nephridium, which is straight and tapers only 

 slightly to the exterior opening, which is very wide and simple. A deep constriction is 

 seen on the outer side of the nephridium. The rim of the nephrostome is thrown into deep 

 crenulations (56 : 9) . The nephridium is rose color with, deeper longitudinal markings 

 (39 : 8) . The nephridia of H. psittacea are quite unlike those of other genera here 

 described, the nephrostomes alone excepted, which bear some resemblance to those of 

 Glottidia. Instead of a long, tapering body with narrow external opening, it is only twice 

 as long as broad and there is only the slightest tapering to the external opening. In the 

 other forms here studied, with the exception of the Lingulidae, the diameter of the 

 nephrostome far exceeds that of the body. In Hemithyris, in one example, the diameter 

 of the nephrostome is the same as that of the body, in another it is narrower than the body 

 (55 : 10, ll) . As Hemithyris has two pairs of nephridia, my two sketches probably represent 

 one of each pair, a point I did not make clear at the time of observation. The axis of the 

 nephrostome is at a slight angle to that of the body, is slightly flaring, and the rim is 

 thrown into deep folds which extend within and are strongly ciliated. A sharp constriction 

 marks the junction of the nephrostome with the body of the nephridium which is short and 

 broad. The surface is marked by a few deep, irregular and anastomosing folds ; these folds 

 mark the boundaries of the lacunae in which an active circulation is seen; 55: 10a shows 

 a much enlarged view of the edge of the nephrostome and 55 : 11a one of the anastomosing 

 folds of the nephridium, greatly enlarged. The marked difference in the form of the 

 external mouths will be noticed ; the " heart of Hancock," as well as certain masses which 

 are probably ova, may be seen attached to the genital band. 



Genital Peoducts. 



In Glottidia, the masses of eggs fill the perivisceral cavity in compact clusters. A 

 transverse section through the intestine shows a ventral mesentery as thick as the walls 

 of the intestine, an inner vascular space is defined, branches are given off to the right and 

 left, and these send out other bands from which the gonads spring. In these masses to be 

 developed into ova, every stage is seen from the small cell to the distinctly micleated egg 



