and Acapidco Sjionges. 289 



p. 179, &c.), I have onlj to repeat here what the occasion 

 seems to require. 



Character. — The group Esperina is mainly characterized 

 by the presence of the //ie^'w^anchorate, which occurs in no 

 other to my knowledge^ except that of Hyndmaniua, where 

 not only the dark brown colour of the sponge itself, but the 

 unique form of one of its flesh-spicules (the " contort bipo- 

 cillated bihamate " of Dr. Bowerbank, Brit. Spong. vol. i. 

 p. 248, fig. 125) is also, to my knowledge, met with nowhere 

 else. The largest inequiauchorate known was found by 

 Schmidt in Espen'a diaphana, from Florida, which measured 

 '•^ 0"65 millim.," about equal to l-40th inch long, while the 

 smaller ones, although still large, only reached " 0T2 millim." 

 = l-222nd inch, which accords more with those in his 

 mounted type specimen now in the British Museum, where 

 the laro-est I could find onlv amounted to a little more than 

 the last-named measurement (Spongf. Atlant. Gebiet. 1870, 

 S. 57, Taf. iv. fig. I'd). Other flesh-spicules occur in Esperia^ 

 viz. bihamate, tricurvate, and the sheaf-like bundles of fine 

 spicules termed " trichites " by Prof. Sollas ; but the pre- 

 sence or absence (perhaps influenced by their scarcity) of one 

 or all of these seems to be as accidental as unintelligible ; so 

 their value in specific distinction is not much : ex. gr., in my 

 mounted fragment of the type specimen of Espjeria [Raphio- 

 desma, Bk., 1870)_/ore«, there is a tricurvate which no doubt 

 belongs to the species ; and in one of Esperia {Bhaphiodes7na, 

 Bk.) lingua there are sheaf-like bundles of trichites, neither 

 of which are mentioned in the descriptions or illustrations of 

 these sponges respectively by Dr. Bowerbank (Brit. Spong. 

 vol. ii. of 1865, illustrated in vol. iii. of 1874). 



Again, the skeletal spicule, although always acuate, is not 

 simply so ; for very often it is sub-pinlike and presents a pecu- 

 liar elongated elliptical inflation, sometimes widened in the 

 centre like a skittle or barrel ; it is also always single — that is, 

 imaccompanied by any other skeletal form ; while the inflation 

 may vary so as to pass from the simple uninflated acuate into 

 the shapes mentioned, even in the same specimen ; hence, if 

 the illustration should be taken from the former it will be 

 acuate, and, if from the latter, sub-pinlike. Thus, in Dr, 

 Bowerbank's illustration of Esperia {lihaphiodesmu) lingua, 

 the form is a simple acuate (Brit. Spong. vol. iii. pi. Lxxvii. 

 fig. 2), while in my mounted fragment of the type specimen 

 in the British Museum it is sub-pinlike or elliptically inflated 

 with a central swelling. Variable, however, as the shape of 

 the obtuse end of the skeletal spicule may be, an avera^-e 

 one may be obtained by extended observation, while the form 



