92 Mr. E. Ray Lankester's Zoological Observations 



Anatomy of Sternaspis. 



Specimens of this interesting worm were from time to time 

 brought to me by the fishermen. Its structure presents no 

 special points of contact with the Gephyrea, but rather with 

 the capitibranchiate polychgetous Annelids, such as Pherusia^ 

 which certainly approach the Gephyrea in the condition of their 

 segment-organs. The closed vascular system contains haemo- 

 globin in solution, and presents an internal series of gills, the 

 structure of which is remarkable in many ways. It would be 

 difficult to make any account of the details of its organization 

 intelligible in this brief summary without illustration. 



Notochordal rudiments in Glycera. 



The observations of Clapar^de on the " drei riesige Roh- 

 renfaden " lying above the nerve-cord in Lumbricus induced 

 me to search, by means of transparent transverse sections, for 

 evidences of a skeletal or supporting arrangement of the con- 

 nective tissue in immediate relation with the nerve-cord in 

 other Annelids. The disposition of the muscles in relation to the 

 sheath of the nerve-cord in Glycera has some interest in this 

 respect, since these parts are seen, in suitably prepared sec- 

 tions, to have generally the same relations as have the muscles 

 and neural sheath, including the notochord, of a vertebrate. 



Terebratula vitrea. 



These most beautiful Brachiopods were sometimes brought 

 in quantities by the deep-sea fishermen. I was not able to 

 obtain the ova in a developing condition. 



There are still many points in doubt with regard to the 

 Brachiopoda, and especially as to the TerebratulidjB. 



This species has not, I believe, been studied in the living 

 state. A young specimen, of the size of a pin's head, exhibited 

 the " arms " in a condition corresponding in general characters 

 with the lophophore of a Polyzoon, with which Mr. Morse's 

 researches on Terebratidina also render it clear that the Bra- 

 chiopod arms are homologous (homogenous). Let me also 

 say here that a comparative study of the structure of the adult 

 arms of Terebratula and of the gill-lamellae of Lamellibranchs 

 leads to the conclusion that these are also homologous (homo- 

 genous) structures. 



The observations of Mr. Barrett on Terebratidina^ and of 

 M. de Lacaze-Duthiers on Thecidium^ are the only ones at 

 present, I believe, as to the condition of the " arms " of 

 Terebratulidae in the living state. 



The cirri are finely ciliated externally ; they are also in- 



