LUCERNARIJ3 AND THEIR ALLIES. 



43 



so far from hindering tlio investigation of their taxonomy, arc of eminent assistance, 

 especially in guiding the eye through their singularly well-disposed ranks. Although 

 they do not actually map out their arrangement on their foundation, they never- 

 theless force themselves upon the attention of the observer, and lead him to infer, 

 at a glance, that they are by no means scattered indiscriminately over the area 

 which they occupy. When they are quiet, and extended in full vigor, the eye is 

 struck with their apparently ranked arrangement, as if they stood in file. Fre- 

 quently the files seem to cross each other in systematic order, like the decussating 

 lines on the milled back of a watch ; but the ranks are particularly noticeable when 

 the body is viewed directly from in front, looking along its axis, as it were {fi<j. 22, 

 and cut no. 1). Tlien one may count as many as eight or ten rows, trending from 

 the proximal to the distal side of the group ; and usually it is clear that one of 

 these rows is more prominent than the others on either side ; that the tentacles 

 composing it are, on tlie whole, larger than in the neigliboring rows. If now tliis 

 file be followed to its distal end, it will be noted that it runs through the middle 

 of the group, or thereabouts — certainly nearer to that line than any otlier file — and 

 that it terminates in the largest tentacle on that side. That is the tentacle which 

 we have spoken of, a few lines back, as the "guide;" it is the primary, single, 

 oldest tentacle. There is no mistaking it, nor its position, in very young animals 

 (^fi<js. 121, 125, no. 1) where the members of a bunch are few. 



Cut L 

 A 11 B 



\ i / 



91. Keeping the main file in view while taking a general survey of a group, the 

 preponderance of the multitude on one side of that row is quite marked ; the oval 

 outline of the bunch appears gibbous ; and if we plunge to the bases of the tentacles 

 we shall find that the area from which they arise is excentric to the oval which 

 circumscribes their tips (cut 3). We naturally infer, therefore, that the general 

 physiognomy is expressive of the arrangement of those details wliich combine to 

 make up tlie whole ; and tliis is true in one sense ; but, as we shall discover 

 presently, the outlying portions are not capable of being reduced to that rigid test 

 Avhich would prove what their real relations are. Their numbers, and, above all, 

 their mobility are serious, insuperable obstacles in the way of such a determination. 

 What at times appears to be a single file is, in reality, formed by the combination 



