742 ON THE YOUNG STACKS OF ECHINI. 



clusively that Echinoneus is only a permanent embryonic stage of Echi- 

 nolampas, thus becoming allied to the Cassidulidae, and that it lias nothing- in 

 common with the Galerites as I would limit them, confining them entirely to 

 the group provided with teeth. This reduces the type to a most natural 

 division, and from what we now know of the simple nature of the ambulacra 

 of all Echini in their early stages 1 would not give to this feature the signifi- 

 cance which it has received, hut would he inclined to unite the tool lied Gale- 

 rites with Echinidae proper in the same suborder, approaching the Clypeas- 

 troids on account of the separation of the anus from the apical system, ami 

 retaining the teeth and general symmetrical structure of the regular Echini; 

 though I am aware that the great development of Galerites in former geo- 

 logical periods, and the relation of the anus and test. may. on further acquaint- 

 ance with living representatives, entitle them to rank as a suborder interme- 

 diate between the Echini proper and Clypeastroids. Young Echinolampadae. 

 measuring a trifle over one eighth of an inch, are elliptical i /'/. A' VI f. i ). re- 

 sembling Echinoneus. with a large transverse elliptical mouth | /'/. XVI. f. .'): 



tin' anus is placed in the truncated posterior extremity above the ambitus. 

 The outline in profile is almost globular {PI. XVI. /. .;) ; each plate of the 

 narrow ambulacra! zone carries a single primary tubercle, surrounded by a 

 circle of miliaries i PI. XVI. f. >, ). The pores are arranged in a vertical row 

 of a single line of pores, three or four for each plate, extending from the 

 mouth to the apex (PI. XVI f. ',). The interanilmlacral plates are elongated 

 horizontally, and carry from one to three principal tubercles, with numerous 

 small miliaries arranged in circles round the primaries, or irregularly scat- 

 tered. In specimens twice the size of the above, the test is less elliptical, 

 more flattened, and the firsl trace of a rudimentary rosette appeals as a short 

 row of double pores extending from the apex, consisting of from eight to nine 

 pairs {PI. XVI. f. e). In one of the poriferous zones of each of the pairs of 

 ambulacra — in the anterior zone of the posterior pair and the posterior zone 

 of the anterior pair of ambulacra — the odd ambulacrum remains simple. In 

 specimens measuring above half an inch this rudimentary one-sided rosette 

 has increased in length, and traces of the second row of double pores are seen 

 in the simple zones near the apex. In specimens measuring an inch these 

 rows have grown to be half as long as the arc of the rosette first formed {PI. 

 XVI. f. ,21) ; the same structure has also extended to the abactinal part of 

 the odd ambulacrum. The elliptical outline is entirely lost in these speci- 

 mens, the shape having gradually become more circular, pentagonal, and 



