N0.1J33. LAXCELETS, etc. FliOM JAPAX-JOEDAX AXD SXYDEn. 727 



and at Misaki (Koajiro Bay) by Dr. H. Nakag-awa. Dr. Ethan A. 

 Andrews further records specimens from Goshinoura. Amakusa, and 

 Buzen. in Kiusiu. Dr. Andrews, on specimens from Kiusiu, counts 

 the nuiscular bands as 37 + 16 + 11 = 64. On the type specimen from 

 Misaki. very carefully counted for us, by Dr. Nakagawa. in the 

 Imperial University, the following numbers were found in a specimen 

 of -15.5 M. 



Right side, 37 + 16 ^ 10 = 63. 

 Left side, 37 + 16 -i- 1 1 = 64. 



The specimens from near Misaki were taken in Koajiro Bay. just 

 north of Misaki. ))y the veteran collector, Kumakichi Aoki, of Misaki, 



The Japanese lancelet is very closely allied to Branchiostotna hel- 

 chiv'i (Gray), {Aiiq>h(o,L'm hdcherl Gray),' from Bass Straits. Accord- 

 ing to Dr. Giinther, the types of this species have the muscular bands 

 37 -|- 14 -|_ 13^ the tail longer and the body shorter than in the Japanese 

 form. It is possible that this ditierence is due simply to errors in 

 counting. In view, however, of the almost entire difference in species 

 in the shore fauna of Japtm and that of Borneo, it seems to us best to 

 regard the Japanese lancelet as a species distinct from B. helcherl. 

 It needs comparison with no other. 



Named for Dr. H. Nakagawa. of Tokyo, well known as an entoinol- 

 oo-ist, in recoo-nition of his excellent work on the present species. 



Class MARSIPOBRANCHII. 



THE MYZONTS. 



Skeleton cartilaginous; the skull imperfectly developed, not sepa- 

 rate from the vertebral cohunn. No true jaw^s, no limbs, no shoulder 

 girdle, no pelvic elements, no ribs. Gills in the form of lixed sacs, 

 without branchial arches, six or more in number on each side. Nos- 

 tril single, median. ^Nlouth subinferior, suctorial, more or less circu- 

 lar. Heart without arterial bulb. Alimentary canal straight, simple, 

 without ct^cal appendages, pancreas, or spleen. Generative outlet 

 peritoneal. Vertical iins with feeble rays, usually continuous around 

 the tail. Naked, eel-shaped animals. inha))iting cool waters, both fresh 

 and salt. They undergo a metamorphosis, the young being often 

 quite unlike the adult. {itapffiTriov. pouch; 0pdyxi(^. gills.) 



OKDERS OF MARyiPOBRANCHII. 



a. Nasal tube duct-like, with cartilaginous rings penetrating the palate; gill ()i)en- 

 ings remote from the head, opening directly into the pharynx; no eyes. 



Hyperolrdi 



aa. Nasal duct a blind sac, not penetrating the palate; gill openings close behind the 



head, conuuunicating with a conunon branchial passage which opens directly 



into the pharynx; eyes well developed in the adult Hyperoartu 



^ Proc. Zool. Soc. London, 1847, p. 35. 



