LIVIN(4 BRACHIOPODA. olJj 



luusculiir attacliiiR'iit. That the coecal tubules are sensory organs of some sort seems 

 highly pi'obahle. Sollas ('86-'87) has figured a coecal tubule, in section, of WaldhebHJa 

 crdiihtiii and shows a strnctare which he interprets as an organ sensitive to tactile 

 impression. In my Embryology of Terebratulina ('7oa), I compared these processes with 

 what I reo-arded as an analo>>'ous structure in the test of Crustacea and considered them 

 as organs of general sensibility. In this memoir I describe and figure in a very early 

 stage of T. septcntrlona/is, verital)le tenuous, hair-like processes, to the number of ten 

 or more, radiatinu' from the distal terminations of the first three tulndes formed. 

 Bennnelen (So) suggests that I may have made a mistake in my observations of their 

 displacement by a delicate brash. 1 can assure tliis accomplished naturalist that tiiere 

 was no mistake ahout the observation, thouo;h I a»;ree with him that the hairs can have 

 no relation to the radiating tubules described by King ('70). In my earlier memoir 

 ('71) I figure and 'describe two short ramifications from the end of one tubule, which 

 are probably compandde with the radiating tubules of King and probably with those of 

 Carpenter ('-"iG). In the early stage of Terebratulina, not only is the shell raised in 

 a shallow collar about the external end of the tubule, but ;i yellowish glandular plug is 

 seen from which radiate these delicate hairs. Claparede ("li'-M figures certain papillae on 

 the elytra of Polynoe with cii'ri terminating in liairs, reminding one strongly of the 

 features above described. In tliis connection it may be interesting to state that Davidson 

 ('86-'88) describes a species of Crania from the Permian of England of which he .says in 

 the dorsal shell, " e.xternally the entire surface is closely crowded l)y a multitude of 

 minute, short, hollow, spinulo.se tubercles which produce a granulated aspect." The 

 manner in which the ridges in Terebratulina coincide with the setae may ex])lain the 

 spinous character in certain forms of Productus and other fossil ln';ichiopods ; but in 

 Crania there are lU) setae, and it would be an interestinu' iniiuirv as to the orio'in and 

 function of these hollow, spinulose tubercles. 



Peduncle. 



The peduncle is a characteristic featiu'e of the Prachiopoda. though wanting in many 

 Testicardine forms ;uid in Crania. That the early stages of this interesting animal will 

 sliow the presence of this structure, there can l)e no doubt. An examination of the shell 

 of Crania sliows no ti'aces of a pe(hnicidar foramen, and it is probabk' that in the young 

 stage the peduncle will be found projecting l)etweeu the shells, as in the Litujulidae. It 

 will Ijc interesting to observe the attitude of the terminal end of the intestine in relati(jn 

 to the peduncle, for in Crania alone, among the braciiiopods, the intestine terminates 

 posteriorly and not at the side, as in Liugula and DiscinLsca. 



