[47] NOTES ON ENTOZOA OF MARINE FISHES. 765 



loose spongy layer of trauverse tissues in the interstices of which the 

 longitudinal fibers lie. The anastomosing branches of this spongy or 

 irregularly reticulated layer unite again at the surface in a rather thick 

 cuticular layer of circular fibers. A few sections further on the follow- 

 ing dimensions occur: central space .3 mm long and .1C" 1 " 1 wide; thickness 

 of circular layer .009 mm ; thickness of reticulated layer .06"""; thick- 

 ness of cuticular layer .014 mm . The aquiferous vessels are here not so 

 much folded. The central space contained the cross section of one 

 pair and the longitudinal section of a coil of the other pair. The 

 remainder of the central space contained some loose areolar tissue. 

 The inner space grows narrower very rapidly as sections proceed from 

 the head, and is speedily reduced to a narrow oblong space or core, 

 enlarging slightly towards the margin, and containing a pair of aquif- 

 erous vessels near each extremity. Each pair of vessels consists of a 

 larger and a smaller vessel, lying side by side, the larger one towards 

 the center of the segment. Between the outer aquiferous vessel and 

 the margin there is a smaller vessel without distinct outliue. These 

 two marginal granular vessels or cords can be traced from the cephalic 

 granular mass. At the base of the head they lie on opposite sides of 

 the rectangular central space and outside the layer of circular fibers. 

 The diameter of one of the larger vessels was .045 mm ; diameter of 

 smaller vessel .032 mm ; diameter of nervous vessel .022 mm ; length of 

 inner core .45 mm ; breadth of section of inner core at middle .022 mm ; 

 thickness of section .4 mm ; breadth of section .6 mui . The narrow core 

 within its limiting layer of circular fibers is composed of granular tis- 

 sue, and is at this point reduced to a very slender line. As the sections 

 proceed the layer of circular fibers which surrounds the central core 

 becomes thinner and in the last sections made, about I 1 " 1 " back of the 

 head, had become almost entirely dissipated, so that the layer of retic- 

 ulated or anastomosing tissue extended from the cuticular layer to the 

 granular core.* 



ECHENEIBOTHRIUM Van Beneden. 



V 



The characters of this genus, according to Diesing, are : 



Body elongated, articulate. Head continuous with the body or separated by a 

 neck with a terminal retractile myzorhynchus. Bothria four, opposite, transversely 

 costato-plicate, sometimes provided with longitudinal partitions, attached, by the 

 posterior margin to the head by means of a contractile pedicel, versatile, unarmed. 

 Os in apex of myzorhynchus. Genital apertures marginal. 



I have separated those species which have the characteristic echeuei- 

 forrn bothria, but are destitute of a myzorhynchus, from the genus 

 Echeneibothi'ium and have placed them in a new genus Rhinebothrium. 



* Dr. J. Niemiec, " Untcrsuchungeu iiber das Nervensystem cler Cestoden," in Ar- 

 beiten aus dem Zoolog. Institute zu Wien, T. vn, pp. 1-GO, Taf. 1 u. 2, 1838, describes 

 the nervous system of Antholothrium musteli. It bears a close resemblance to that 

 which I have made out in A. pulvinatum. 



