The table of classification here appended is that suggested by Mr. Davidson in his Monograph on the Recent Brachiopoda.
| I. TESTICARDINES | |
|---|---|
| Family | |
| A. Terebratulidae. | This includes the majority of genera and of species, the latter, without counting uncertain species, amounting to sixty-eight. Examples: Terebratula, Terebratella, Terebratulina, Waldheimia, Megerlia, Argiope, Cistella. |
| B. Thecidiidae. | This family contains one genus, Thecidium, with two species. |
| C. Rhynchonellidae. | This family is made up of eight species, six of which belong to the genus Rhynchonella, and two to Atretia. |
| II. ECARDINES | |
| D. Craniidae. | This family comprises the four species of Crania. |
| E. Discinidae. | This family contains one species of Discina and six of Discinisca. |
| F. Lingulidae. | This family consists of eight species of Lingula and three of Glottidia. |
It is impossible to come to any satisfactory conclusion as to the position of the group Brachiopoda with relation to the rest of the animal kingdom. They have, in accordance with the views of various investigators, been placed in close connexion with many of the large groups into which the Invertebrates are split up. The Mollusca, the Tunicata, the Polyzoa, the Chaetopoda, the Gephyrea, and of recent times such isolated forms as Phoronis and Sagitta, have all in turn had their claims advanced of relationship to this most ancient group. As far as I am in a position to judge, their affinities seem to be perhaps more closely with the Gephyrea and with Phoronis than with any of the other claimants; but I think even these are too remote to justify any system of classification which would bring them together under a common name. Investigation into the details of the embryology of the group, more especially into that of the Ecardines, might throw some light on this subject, and it is much to be desired that this should be undertaken without delay. That the group is a most ancient one, extending from the oldest geological formations, we know, that the existing members of it have changed but little during the vast lapse of time since their earliest fossil ancestors flourished, we believe; but we are in almost total ignorance of the origin or affinities of the group, and we can hardly hope for any light on the subject except through embryological research.
BRACHIOPODA
PART II
PALAEONTOLOGY OF THE BRACHIOPODA
BY
F. R. COWPER REED, B.A., F.G.S.
Trinity College, Cambridge