APPENDIX. 



By Sidney F. Harmer, B.A., B.Sc, Fellow of King's College, Cambridge, and of 



University College, London. 



The following observations on Cephalodiscus were made in consequence of a letter 

 received from Professor M'Intosh, calling my attention to certain remarkable features 

 in tlie anatomy of the genus. I am very greatly indebted to Professor M'Intosh for his 

 courtesy in giving me specimens of Ce2)halodiscus, and most of all for his kmdly 

 expressed destre that I should publish my conclusions as an appendix to his own mono- 

 graph. Time has not permitted of my seeing the proofs of this monograph, and I must 

 therefore claim indulgence for any descriptions which 

 would otherwise appear unnecessary repetitions of 

 the results of Professor M'Intosh himself. 



In examining sections of Cephalodiscus, I have 

 been struck with the existence of various organs which 

 appear to me to point to the conclusion that this 

 remarkable genus is a near ally of Balanoglossus. 

 This very unexpected result will be understood by 

 comparing the following woodcuts (with the remarks 

 which accompany them) with Bateson's papers on the 

 anatomy and development of Balanoglossus} 



Fio-. 1 represents a longitudinal, right and left, 

 section of a young bud of Cephalodiscus. The re- 

 semblance between this section and Bateson's diagrams 

 of the larvae of Balanoglossus^ is, in all essential details, exact. The body of the 

 young Cephalodiscus is divided, by means of two transverse grooves, into three well- 

 marked regions. Of these the anterior (p.) may be compared to the proboscis of 

 Balanoglossus; the middle division (c.) to the collar of the same animal, and the posterior 

 division (tr.) to the trunk or body. It will further be noted that the proboscis is pro- 



1 Qmrt. Journ. Micr. Sci., vols, xxiv., xxv., xxvi. 



2 Quart. Journ. Micr. Sci., vol. .\xvi., pi. xxxiii. fig. 7. 



Fig. 1.— p., r™l"'scis ; c, collar; tr., trunk; 

 ai., alimentary canal ; nch., notochord ; 6.c.i, 

 body-cavity of proboscis ; b.c", body-cavity 

 of collar ; b.c.^, body-cavity of trunk. 



