GOO E. W. MACI31UDE. 



22. MouTENSEN. — "Die Ecliiiiodcnneiilarven der Plaukton Expedition," 



' Ergeb. der riankton Exp.,' 13d, 2, J. 



23. MouTENSEN. — " Die Echiiiodcrnieularvcn," ' Nordisclies Plauktou,' ix, 



1900. 



24. MiJLLER, J. — " Ueber einige neue Tliierformeu der Nordsee," ' Arcli. 



Anat. u. Pliysiol.,' 1840. 



25. MiJLLEii, J. — " Ueber die Larveii und die Metamorpliose der Opliiurcii 



uud Seeigel," ' Koiiig. Akad. Wiss. zii Berlin,' ISiG. 



26. MiJLLER, J. — " Ueber die Larveii uud die Metamorphose der llolotliuricn 



und Asterieii," ' Konig. Akad. Wiss. zu Berlin,* 1850. 



27. MiJLLER, J. — "Ueber die Opiiiurcniarven des Adiiatisclieu Meeres," 



Konig. Akad. Wiss. zu Berlin,' 1851. 



28. MiJLLER, J. — " Ueber den allgcmcineii Plan in der Eutwieklung der 



Ecliinodermen," 'Konig. Akad. Wiss. zu Berlin,' 1852. 



29. Russo, A. — " Embriologia dell' Atnphiura squamata (Sars)," 'Alti. 



dell B. Acadeniia dell Sc. fis. e mat. di Napoli,' vol. v, series 2, 1891. 



30. ScuuLZE, M. — " Ueber die Eulwicklung von Opliiolepis squamata," 



'Arcli. Anat. u. Physiol.,' 1851. 



31. Selenka, E. — " Keimbliil-ter der Ecliinodermen,'' ' Studien iiber Entwick- 



lung der Thieren,' Wiesbaden, 18S3. 



32. WoLTEiiECK, R. — " Wurm-'kopf,' Wurmrumpf und Trochophora," ' Zool. 



Anzeiger,' lid. 28, Nos. 8 and 9, 1904. 



33. ZiEGLEii, II. E. — " Einige Beobachtungen zur Entwicklungeschichte der 



Ecliinodermen," ' Verli. der deutschen Zool. Ges.,' 189G. 



EXPLANATION OF PLATES 31-36, 



Illustrating Professor E. W. MacBride's paper '' Ou the 

 Development of Opliiothrix fragilis." 



List op Abbreviations Employed. 



The Arabic numerals 1 — 5 are employed to denote the lobes of the left 

 liydioccele. When a dash is added to the numeral, thus — 1', 2', etc. — a lobe of 

 the right hydrocoele is indicated. The Roman numerals I— V arc employed to 

 denote the developing arms of the adult. In all cases the numbers commence 

 with the lobe or arm which is situated in the larva farthest forwards and the 

 enumeration proceeds backwards. 



al. Antero-lateral arm of larva. az. I. Azygous lenlacle of the young 

 0()liiurid. d. t. Buccal tentacle of the young Opliinrid. ril. Longitudinal 



