588 THE ANIMAL KINGDOM. 



and the remainder are divided on the ventral aspect, by a median and two lateral 

 fissures, into a large dorsal and two smaller ventral plates. The terminal or anal 

 ring is usually forked. Most of the rings carry spines, the last usually two of 

 great length, more seldom one. A nervous system is represented by a right and 

 left band, which unite anteriorly (Greeff) ; and two to eight red eye-specks lie upon 

 the bands. Reinhardt, however, states that he could not find the nervous bands, 

 but found instead four glandular caeca opening into the proboscis. The mouth is 

 anterior and terminal, and leads into an eversible proboscis, armed at its apex with 

 six to eight two-jointed spines ; there is a muscular oesophagus, with a circlet of 

 small spines at its commencement, an intestine, and terminal anus. Excretory 

 organs are represented by a pair of sacs in the ninth segment ; they end in ciliated 

 ducts, which open separately on the latero-dorsal aspect of the tenth segment. The 

 sexes are separate. The testes and ovaries are paired and saccular; they open 

 terminally. Greeff considered the animal to be viviparous, but Reinhardt states 

 that he mistook the testes with their contents for ovaries. There is a single genus, 

 Echinoderes, with several species. 



Reinhardt, Z. A. iv. 1881 Greeff, A* N. 35 (i), 1869; Panceri, Atti Accad. 

 delle Scienze, Naples, vii. 1878, No. 10, p. 4. 



4. Desmoscoleddae. Minute, marine, vermiform, with the body contracting 

 .both in front and behind. The head is somewhat globular ; the body is girt by a 

 series of rings, varying in number in the different species. There are four setae on 

 the head, and a pair on more or fewer of the body-rings, some dorsal and some 

 ventral ; they are capable of independent motion. There are two eye-specks, but 

 no nervous system is known. The mouth is anterior and terminal; there is a 

 muscular oesophagus, a straight intestine, and an anus on the dorsal aspect, 

 according to Greeff. The sexes are separate ; the testis and ovary are single and 

 saccular ; the former opens into the anus, and has two chitinoid copulatory spiculae ; 

 the latter opens anteriorly to the anus on the same aspect (Greeff). There is a 

 single genus Desmoscolex, with several species. The genus Trichoderma (Greeff), 

 which has no setae, but is covered with long hair-like processes, is perhaps related 

 to Desmoscolex. The male has two spiculae. Both genera are in some respects 

 like the Nematoda. 



Greeff, op. cit. supra, and Panceri, op. cit. p. 2 and p. 7 ; Reinhardt, Z. A. iv. 

 1881, p. 591. 



5. Chaetosomidae. Minute ; partly marine, partly freshwater. There are three 

 genera, Chaetosoma, Tristicochaeta, and Rhabdogaster. The first-named has an oval 

 head, and a body pointed posteriorly. The head has a double row of moveable 

 hooks, arranged in a semi-circle ; and it is covered, as also the body, with a number 

 of fine hairs. Locomotion is effected by a double row of knobbed rods anterior to 

 the anus. The mouth is anterior and terminal ; there is a muscular oesophagus, 

 an intestine, and a rectum, with a ventral anus. The sexes are separate. The 

 testis is a single sac ; the vas deferens opens with the anus, and has two chitinoid 

 copulatory spicules. There are two ovaries, with a single vagina opening ventrally 

 about the middle of the body. Tristicochaeta (Panceri) resemble Chaetosoma very 

 closely, but has three rows of locomotor rods. Rhabdogaster has the head not 

 marked off from the body, but it is somewhat dilated, like the genital region. The 



