790 



SCIENCE. 



[Vol. II., No. 46. 



been ascertained. A common mode of propagation 

 of Urnatella appears to be by budding, the formation 

 of branches with their terminal polyps, and the de- 

 tachment of these branches to establish stocks else- 

 where. The different specimens apparently indicate 

 this process, though it was not actually observed. 



Though the stem of Urnatella is invested with a 

 firm, chitinous integument, it still retains its flexibil- 

 ity; so that, when the polyp is disturbed, it not only 

 closes its bell, and bends its head, but the entire stem 

 bends, or even becomes revolute. Sometimes the 

 polyps suddenly twist the stems from side to side, as 



Fig. 2. — TJrnatella gracilis, with the main stem of four segments, 

 and a terminal expanded polyp. Branches ai-e' given off hy 

 the third segment, and a bud from the fourth. 



if they had become wearied of remaining longer in 

 the same position. 



The interior of the polyp is mainly occupied by the 

 alimentary apparatus. From the mouth of the bell 

 a funnel converges as the pharynx; and the tube of 

 the former, as the oesophagus, occui^ies the shorter 

 side of the bell. At the bottom of the latter the 

 oesopliagus opens into a capacious retort-like stomach, 

 which occupies two-thirds of the capacity of the 

 polyp. The stomach towards the mouth of the bell 

 has an alembic-like pylorus, from which a short in- 

 testine turns ventrally to expand in an oval colon. 

 From this a short rectum opens about the centre of 

 the mouth of the bell. The pharynx, oesophagus, 

 and stomach are lined with ciliated epitlielium. The 

 ventral side of the stomach has the epithelium 

 colored brown, indicating, as in other polyzoa, an he- 

 patic function. The polyp feeds on vegetable par- 

 ticles mainly, including diatoms, desmids, etc. ; and 

 the food may be observed in an incessant whorl in 



the axis of the stomach, induced by the action of the 

 cilia lining the latter. The polyp is almost constantly 

 infested with parasites, often in large numbers, which 

 mingle with the food, and accomp.any this in its move- 

 ment. The parasite is a ciliated infusorian, distin- 

 guished with the name of Anoplophrya socialis. 

 From time to time, remains of the food are passed into 

 the colon, and here accumulated into an oval pellet, 

 which is then quickly discharged from the mouth of 

 the bell. 



Generative organs, or provision of any kind for the 

 production of ova, were not detected, nor were eggs 

 observed. 



Urnatella differs from the marine genus Pedicellina 

 mainly in not having an attached and creeping root- 

 stalk, and in having free, pendent, and jointed stems, 

 instead of simple pedicles. 



THE PHYLOGENY OF THE HIGHER 

 CRUSTACEA. 



The claS? Crustacea is one of the dominant groups 

 of the animal kingdom, and it includes a very con- 

 siderable proportion of our living animals. Its repre- 

 sentatives are extremely diversified in structure ; and 

 a single order, such as the Decapoda, includes a much 

 greater variety and diversity of forms than the whole 

 class of insects. It is very rich in primitive and transi- 

 tional forms; and when we add to this, that there 

 is no group in which our embryological knowledge is 

 more rich and varied, or in which the embryological 

 history of the individual throws so much light upon 

 the evolution of the race, its importance as a means 

 for tracing the actual history of the evolution of 

 species is obvious. In fact, most of the problems in 

 the logic of morphological reasoning, are, in great part 

 at least, problems in the morphology of the Crus- 

 tacea. 



Since the awakening in natural science which fol- 

 lowed the publication of the Origin of species, many 

 naturalists have attempted to disentangle the story of 

 the phylogeny of the Crustacea. Some of these at- 

 tempts, such as Miiller's ' Fiir Darwin' and Huxley's 

 'Crayfish,' are familiar to all; while others, such as 

 Claus' ' Crustaceen system,' are known to none except 

 specialists. The latest attempt in this field ( " Studien 

 iiber die verwandtschaftsbeziehungen der Malakostra- 

 ken," by Dr. J. E. V. Boas, Morph. jahrb., viii. 4, 

 1SS3) is, to say the least, a very valuable addition to 

 crustacean morphology, as well as an interesting 

 study in scientific logic. Its results seem to be a close 

 approximation to the true natural classification of the 

 higher Crustacea, and it should therefore receive the 

 careful attention of all naturalists, and of all who wish 

 to be informed regarding the methods of thought in 

 morphology; but as it is from necessity filled with 

 minute details, which would be formidable to all 

 except specialists, the general reader must be con- 

 tented with a summary of the results. 



The proof that the crabs are descended from long- 

 tailed decapods is familiar to all naturalists; and no 

 one can doubt, that, among these, the swimming dec- 



