28 Coelenterata. 



The skeletal sheath is very thin, and the ectoderm and endoderm similar in 

 structure; there is often a fusion between the top of the spine-sheath and the 

 body wall, the mesogloea of both parts being confluent. The stomodseum does 

 not possess a differentiated sulcus, dark pigment is present especially in its 

 lower part; there may be longitudinal muscles in the ectoderm and circular 

 ones in the endoderm, but there is no distinct sphincter. The mesenteries 

 are generally uniform in number (10) and position but in one case (contorta) 

 there are 12; thus in one genus the characters of both of Schultze's subfami- 

 lies - - Decamerota and Dodecamerota (Leiopathes] - - are represented. The 

 secondary mesenteries usually extend furthest down the body wall, an indication 

 that they are not rudimentary. The mesoglcea of the mesenteries is raised 

 into ridges (sometimes with secondary outgrowths) to support the muscle 

 fibres. Usually both pairs of sagittal and the frontal (first) pair of second- 

 ary mesenteries face anteriorly, the transverse and the hinder pair of se- 

 condary mesenteries face posteriorly. But differences may occur in members 

 of the same colony. In the transverse mesenteries the muscle bands are best 

 developed, in the others they are more slender, especially in the sagittal me- 

 senteries in which they are often difficult to find. The 6th pair of mesenteries 

 has no muscle fibres; in one species muscle fibres were totally absent. The ar- 

 rangement of the muscle bands of the mesenteries, symmetrically with regard 

 to the longer axis of the stomodseum, is more in agreement with Brook's, than 

 with Schultze's view of the body-axes. Each mesenterial filament is single lobed 

 and has the same structure as the stomodseum. Filaments are present on the 

 transverse mesenteries, often on the sagittal and occasionally on the secondary 

 ones, but only those of the transverse ones are forked and convoluted. As a 

 rule gonads are borne only by the transverse mesenteries but in contorta well 

 developed ova were also present in the frontal secondary ones. The gonads 

 are situated unilaterally on the mesenteries. The ova have no (or a very 

 thin) mesogloeal capsule but each testis is enclosed in a thick capsule, which 

 eventually bursts and liberates the sperms into the coelenteron. The formation 

 of new polyps was observed on the oral cone of an adult polyp of contorta. 

 Some species have parasitic algae in the ectoderm and endoderm. The author 

 regards the Antipatharia as primitive forms; the differences between them 

 and Ceriantharia are too great to justify their combination into one group 

 Ceriantipatharia. C. is phylogenetically younger than the Ramosse. 



K. Kinoshita( 3 ) describes Hexapathes n. heterosticha n., from Sagami Bay (400 

 fathoms). In its mode of branching and the form of its polyps it closely re- 

 sembles BathypatJies, but does not possess the sulco- and sulculo-lateral mesen- 

 teries which, according to Schultze, are an important character of B. There 

 are in H. two pairs of directive and a pair of lateral mesenteries, the stomo- 

 dseum is long, nearly reaching the axis sheath. H. is placed in the Clado- 

 pathinse, a subfamily of the Antipathidse. 



Thomson ( 3 ) describes some of the structural features of Dendrobrachia fallax, 

 from 219 fms. off the island of St. Vincent (Cape Verde Islands). The axis, 

 which is without central canal, consists in its younger parts of 5 longitudinal 

 ridges or plates standing out from a thin central stem. Later the ridges in- 

 crease in number, and by deposition of horny substance the troughs between 

 the ridges are filled up. The polyps, which arise laterally, often in sub-oppo- 

 site pairs, are more distant from each other than is usual in Antipatharians, 

 and they are often appressed. The tentacles are retractile and bear 6 to 8 pairs 

 of pinnules. There are 8 mesenteries. The author considers /". to be a primitive 

 Antipatharian and nearer than any to the Zoantharian stock. See also Summers. 



