INVERTEBEATA, CRYPTOGAMIA, MICROSCOPY, ETC. 567 



were undoubtedly fixed in the earlier periods of their time- history, this 

 radiate character is, in them, just as in certain fixed Annelids or the 

 fixed Tunicate {Odacnemua) described by Mr. Moseley, probably due 

 to their mode of life. The views of Haeckel as to the colonial character 

 of these forms, and of Alex. Agassiz with regard to their affinities to 

 the Ctenophora, are rejected : the Gasterotricha and the Nematodes 

 {Vermes arcMcoelomati), the Platodes (by degeneration V. accelomati) 

 as well as the Nemertini and the Bryozoa are regarded as close allies 

 of Trochozoon ; while as to the Brachiopoda, which are regarded as 

 Molluscoidea, and as to the Mollusca proper there appears to be suffi- 

 cient evidence of their rightful position in a similar category ; the 

 Nemertinea are, in the adult stages, difficult forms, but the Pilidium 

 larva is sufficiently indicative of their phylogeny. 



The adult Annelides are characterized by the development of the 

 dermo-muscular tube, the formation of the secondary coelom in the 

 trunk, and the appearance of the ventral ganglionic cord, after the 

 development of the supra-oesophageal ganglia ; with these the Arthro- 

 poda are regarded as undoubtedly connected, while the absence of 

 any Trochozoon-like larva is explained by the characters of the 

 Nauplius, in which the presence of chitin in the cuticle and of the cha- 

 racteristic locomotor appendages are sufficient reasons for the absence 

 of cilia. 



Dr. Hatschek has no doubt as to the correctness of the views of 

 Anton Dohrn as to the degraded character of the Tunicata of the 

 present day, and as to their direct relations to tlie Vertebrata on the 

 one hand, and the unsegmented Worms on the other. As to the 

 Annelides and Vertebrata there are ample indications of their 

 affinity ; neither the dorsal region nor the mouth are homologous, but 

 in the rudiments of their nervous apparatus, of their circulatory system, 

 of their renal organs, and of the disposition of the muscular tracts 

 there is ample evidence ; the sensory organs are arranged on the same 

 plan, and the only point of difference in their renal organs is the 

 retention by the Vertebrata of the unsegmented excretory canal. The 

 two groups are regarded, finally, as having had a common ancestor, 

 less differentiated than Poli/gordiiis, from which the Vertebrata have 

 most strikingly diverged by the development of a chorda dorsalis of 

 endodermal origin, and by the formation of a new mouth and of bran- 

 chial clefts, coupled with the loss of the primary oesophagus. 



Anatomy of Magelona.* — Dr. W. C. Mcintosh's paper on this 

 subject (published in abstract by the Eoyal Society) finds a home in a 

 German journal. 



The animal in question, long since known to Johnston, but only 

 described by name (Mcea mirabilis) in the British Museum Catalogue 

 of Worms (1865), was made known to science by Fritz Miiller in 

 1858. Found in large quantities at St. Andrews, it has also been 

 found at Southport ; from 150-200 mm. long, it is of a pale rose 

 colour anteriorly, and of dark greyish-green posteriorly ; the cephalic 

 lobes are eyeless, considerably flattened, and diminish towards the 



* ' Zeitschr. v/ua. Zool.,' xxxi. (1878) p. 401. 



