7t>6 PROCEEDINGS OF THE NATIONAL MUSEUM. vol.xxih. 



Order AMPHIOXI. 



THE CIRROSTOMES. 



This order is equivalent to the family Branchlostom khe. {ai.i<J)i. l)oth ; 

 oBv5. sharp: Cirrostomi is from c/'rrus, a look of hair; ffro/ia^ mouth.) 



Family I. BRANCHIOSTOMID.E. 



THE LANCELETS. 



Body elongate, lanceolate, compressed, naked, colorless; the tins rep- 

 resented I)}' a low fold extending along the back, with usually a rudi- 

 mentary fold l)elow which passes by the vent to the a)>dominal pore. 

 Mouth inferior, appearing as a longitudinal lissure, surrounded by 

 conspicuous, rather stiti', cirri. Eye rudimentary. Liv^er reduced to 

 a blind sac of the simple intestine. Small, translucent creatures found 

 embedded in the sand on warm coasts throughout the world. The 

 species are all very similar in appearance and hal)its, and the numbers 

 of the muscular impressions furnish the only characters thus far known 

 by which the species can be distinguished. 



«. Gonads (reproductive structures) present on both sides of the median hue; anal tin 

 present with traces of tin rays; no caudal process Brancjiiostoma, 1 



1. BRANCHIOSTOMA Costa. 



BnuicJiiostojmtCosTA, Cenni ZoologiciXapol., 1834, p. 49 (liunbricinn^koiceulatinii ). 

 Amphioxus Yakrell, British Fishes, 1836, p. 468 {lanceolatus). 



Lancelots with the gonads or reproductive structure present on both 

 sides of the median line. Anal tin present, with traces of rays. Ver- 

 tebral column not produced backward into a caudal process. Six or 

 seven species recognized, found in the warm seas, usuallv buried in 

 sand flats at no great depth. The}' are very tenacious of life, and will 

 endure considerable mutilation. (/tfprt';KJ^^, gills: ffro/na. mouth — the 

 cirri about the mouth having been taken for gills b}' Costa.) 



o. Myocommata or muscular bands, 62 to 64. 



h. Myocommata behind vent, 10 or 11, the formula usually 37 — 16 4- 

 11 =64 Xakaoaw.k, 1 



I. BRANCHIOSTOMA NAKAGAWiE Jordan & Snyder, new species. 



AmphioxuK sp. Andrews, Zool. Anzeiger, 1895, p. 468, Goshi-no-ura, Amakusa, 



Buzen. 

 Amp}iio.rui< sp. Nakagawa, Annot. Zool. Jap,, I, 1897, \>. 127. Goshi-nu-iira in 



Higo, Shikajima in Chikuzen. 



Muscular bands, 37 + 10 + 11 = 64. Usual length, 1 to 2 inches. 

 Bod}^ relatively long, the tail short, the form rather stout. Sandy 

 coasts of Japan, from Misaki southward to Kiusiu, our specimens from 

 Misaki, presented by Dr. Mitsukuri. Others in Imperial University 

 collected at Bungo by Dr. S. Matsubara, at Shikajima, by Dr. S. Hatta, 



