LIVING BRACHIOPODA. 315 



Note of explanation. I have used the terms Testicardines and Ecardines as they are 

 in common use, and the forms they include are well known. They parallel Owen's divi- 

 sions of Arthropomata and Lyopomata, as well as those of Huxley's Articulata and Inarti- 

 culata. The names proposed by King, Gill ('73), and others also include the same chvi- 

 sions. As Beecher ('92) says in referring to Huxley's definitions, '• these names may be 

 conveniently retained as two divisions or sub-classes, but they fail to express the true rela- 

 tionships of the various groups included iu them," so the terms Testicardines and Ecar- 

 dines are used simply as convenient names to designate certain well known forms. In 

 justice to Beecher, I must say here that the classification proposed by tliis naturalist rests 

 on such a profound and varied comparison of the fossil as well as the recent forms that it 

 may well be accepted as the latest and best expression of the relationships of these ani- 

 mals. If he were compelled to bring his four groups into two divisions, however, he 

 would certainly group Atremata and Neotremata together, which would give us the Inarti- 

 culata, or the Ecardines, and his Protremata and Telotremata, which would give us the 

 Articulata or Testicarchues. The works of Beecher and Schuchert are above all the most 

 painstaldng and philosophical studies of these fascinating animals yet given. 



In referring to Glottldia pyramidata I have used the generic term only, to avoid the 

 repetition of the long specific name. In every instance, then, the word Glotticha is used 

 for the species ^j?/r«y»ir/a^fl. Judging from the well marked characters of the shell of 

 Glottidia alhida, a Pacific coast form, I have no doubt that the internal structure will be 

 found to be the same as in the Atlantic coast species. 



For convenience of reference I have used the term coelomic cavity without asserting 

 that it is the true coelom. Iu order to be exphcit, I have at other times used the terms 

 perigastric and periA-isceral cavity. I have also used the word Ijlood to indicate the only 

 circulating fluid I have seen in living Bracliiopoda. Perivisceral fluid, perienteric fluid, 

 chylaqueous fluid, and other terms might be more exact or perhaps less committal, but 

 when the term blood is used it will be understood to imply the fluid, charged with various 

 corpuscles, which is seen circulating within the tissues. 



References to the plates and figures are given by numbers only ; thus 49 : 8 means 

 plate 49, figure 3. In this way is avoided the repetition of the words plate and figure, 

 or their abbreviations. 



In all cases, unless otherwise explained, the figures are di-awn with their dorsal 

 region uppermost, if seen from the front or side ; and if seen from the dorsal or ventral 

 side, the anterior region is uppermost. With two exceptions, all the figures are exact 

 copies of my original sketches ; hence many of the drawings are incomplete, some of 

 them being mere sketch memoranda. 



