578 



SCIENCE. 



[N. S. Vol. XV. No. 380. 



into the dorsal vessel in segment X. and, 

 by way of the pai'ietals, in segments XII. 

 and XIII. This system is to be considered 

 as representing the parietal vessels of the 

 region in front of the last pair of hearts. 



A Contribution to the Arterial System in 

 Cryptohranchus : H. H. EIeener. 

 Presented by J. B. Johnston. (Read by 



title only.) 



The Larva of Naushonia crangonoides: 



MiLLETT T. Thompson. 



It was my good fortune, while at Woods 

 HoU last summer, to identify and rear the 

 larvse of Naushonia crangonoides (Kings- 

 ley), a small Thalassinid Crustacean taken 

 near Wood's HoU in 1893. 



Tliree zoea and two mysis stages are 

 recognizable, during which stages the met- 

 amorphosis is inconsiderable, the 'habit- 

 us ' being similar in all. The mysis phase, 

 however, closes with a sharp change, the 

 adolescent phase resembling the adult more 

 closely than is usual among the Crustacea. 

 The zoea and mysis phases of this species 

 are distinguished from all other known 

 Crustacean larvas— with two exceptions — 

 by their peculiar form. The carapax is 

 elongated beliind the eyes into a 'neck' ; the 

 rostrum is short and arcuate; the body is 

 without spines, though the anterior abdom- 

 inal segments bear hook-shaped processes 

 at their posterior angles ; the sixth segment 

 of the abdomen is very elongate. The 

 mandibles are remarkably asymmetrical, 

 although symmetrical in the adolescent 

 stages and hence probably in the adult. 



Two other larvse resemble these in form; 

 a larva of unknown parentage from the 

 English coast, in regard to whose mandi- 

 bles data are lacking; and the well-known 

 larva of Calliaxis adriatica (Heller). The 

 mandibles of the latter are like those 

 of the Naushonia larva in shape, and sim- 

 ilarly the one on the left is hook-shaped 

 and the one on the right conical. Leaving 



out of the question the too little known 

 English form, we find that the likeness 

 between the larvas of Naushonia and those 

 of Calliaxis is not due to convergence, but 

 to a close relationship existing between the 

 species. This is easily demonstrable by 

 comparing the adults of the two species. 



Calliaxis and Naushonia do not seem to 

 be very closely related to the other species 

 grouped in the Thalassinidea, excepting 

 possibly Laomedia (DeHaan). They per- 

 haps represent a group which has 

 approached the Thalassinidea in some 

 respects, but whose descent must be sought 

 along a different line from that of the 

 other genera of this group. 



On the Spinal Homologues of the Cranial 

 Nerve Components: J. PijAyfaib Mc- 



MURRICH. 



The researches of Strong and C. J. Her- 

 rick have demonstrated the existence in 

 the cranial nerves of five distinct compo- 

 nents which may be termed the lateral 

 line, somatic sensory, viscero-sensory, 

 median motor and lateral motor com- 

 ponents. The first of these are undoubt- 

 edly confined to the cranial region, but of 

 the other four it seems probable that 

 homologues exist in the spinal nerves. The 

 somatic sensory components, being sup- 

 plied to the skin, are naturally to be 

 homologized with the components of the 

 dorsal spinal roots which have a similar 

 distribution, and the equivalents of the 

 viscero-sensory fibers, distributed to the 

 endodermal sense-organs and epithelium, 

 are to be looked for in those sensory fibers 

 from the posterior root ganglia which 

 accompany the efferent fibers of the sym- 

 pathetic system to the viscera. 



As regards the two motor components, 

 the homologues are not so apparent. The 

 observations of van Wijhe have shoA^^l that 

 the cranial muscles belong to two cate- 

 gories, the musculature of the branchial 



